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THE LIBRARY OF 

CONGRESS, 
One Copy Received 

JAN, 8 1902 

Copyright entry 
ICLASS d XXc No. 

** ■) is- 

COPY B. 



Copyright, 1901, by 

The Westinghouse Air Brake Company 

Pittsburg, Pa. 



• • •. 

• • • • 



• •• ••• •• 




AIR BRAKE 
INSTRUCTION BOOK 

OF 

THE WESTINGHOUSE 
AIR BRAKE 
COMPANY 



OFFICERS 

George Westinghouse, - President 

H. H. Westinghouse, - - - Vice-President 

E. M. Herr, ----- General Manager 
W. W. Card, - - Secretary 

John Caldwell, ----- Treasurer 
John F. Miller, - - - Assistant Secretary 



Pittsburg, Pa., 1901 



INDEX. 

Page. 

Preface, . . . . . .3 

Westinghouse Quick - Action Automatic Brake — 

General Description, ... 5 

Nine and One-half-inch Air Pump, . . .11 

Eight-inch Air Pump, . . . . 15 

Air- Pump Governor, . . . . 19 

Main Reservoir, . . . . .22 

" G-6 " Engineer's Brake Valve, . . .24 

Slide-Valve Feed Valve, .... 32 

Old-Style Feed Valve, . . . -37 

" D-8 " Engineer's Brake Valve, . . 39 

Quick-Action Triple Valve, . . . -47 

Plain Triple Valve, . . . . 52 

Combined Freight-Car Cylinder, Reservoir and Triple 

Valve, 55 

Pressure- Retaining Valve, ... . 58 

Piston Travel, . . . . .61 

Automatic Slack Adjuster, . . .64 

Train Air-Signal System, . . . 71 

High-Speed Brake, .... 76 

Automatic Reducing Valve, . . . 78 

High-Pressure Control, or Schedule U, . 84 

Handling Brakes in Train Service, . . 87 

Piping, ...... 93 

Lubricants, . . . . . -93 

Brake Inspection and Maintenance, . . 94 

Foundation Brake Gear, . . . .98 

Leverage, . . . . .101 

American Driver Brake, . . . .114 

Cam Driver Brake, . . . . 117 

Locomotive-Truck Brake, . . . .118 



PREFACE. 

The present edition of our Instruction Book is in the 
nature of a revision of our previous publications. It has 
been our aim to condense and simplify the descriptive 
matter as much as possible, and at the same time to present 
a complete description of the parts and their operation 
in the air-brake and air-signal equipment. In it will be 
found illustrations and explanations of the new devices, as 
well as of any modifications of older appliances which have 
been made with the idea of furnishing the best possible air- 
brake and air-signal equipment. 

We have distributed many thousand copies of previous 
editions of our Instruction Book among railway officers 
and employees in this and other countries, the net result 
of which has been the education of railroad men in the 
subject of air brakes, to such an extent that we are led to 
believe that much of the matter heretofore published can 
be consistently omitted, especially as there are now many 
other publications which deal with brake subjects at 
greater length and provide a source of information in de- 
tail, which may be referred to, if desired. For this reason, 
the present edition of our Instruction Book has been some- 
what abridged and presents a terse description of the func- 
tions and methods of operation of the devices supplied by 
this company for the equipment of railroads with its air- 
brake and air-signal apparatus. 

We shall, in the future, as in the past, be pleased to 
furnish these books gratuitously, upon request of heads of 
departments. 

The Westinghouse Air Brake Co, 
November, 1901. 



The 

American 

Machinist 

Press 

NY. 



The Westinghouse Quick-Action Automatic 

Brake* 

General Description. 

The Westinghouse Quick-Action Automatic Brake 
consists of the following essential parts : 

First — The Steam-Driven Air Pump, which supplies 
the compressed air. 

Second — The Main Reservoir, in which the com- 
pressed air is stored. 

Third — The Engineer's Brake Valve, which regulates 
the flow of air from the main reservoir into the trainpipe 
for charging and releasing the brakes, and from the trainpipe 
into the atmosphere for applying the brakes. 

Fourth — The Air Gauge, which, being of the duplex 
pattern, shows simultaneously the pressures in the main 
reservoir and in the trainpipe. 

Fifth — The Pump Governor, which regulates the sup- 
ply of steam to the pump, stopping it when the maximum 
air pressure desired has been accumulated in the air-brake 
apparatus. 

Sixth — The Trainpipe, which connects the engineer's 
brake valve with the main-reservoir and with each triple 
valve in the train, and includes flexible hose and couplings 
between cars. 

Seventh — Th* Auxiliary Reservoir, which is supplied 
with air from the main reservoir, through the trainpipe and 
triple valve, and stores it for use upon its own vehicle. 

Eighth — The Brake Cylinder, the piston rod of which 
is connected to the brake levers in such a manner that, when 
the piston is forced outward by air pressure, the brakes are 
applied. 

Ninth — The Quick-Action Triple Valve, which is 

(5) 



6 WESTINGHOUSE QUICK-ACTION AUTOMATIC BRAKE. 

suitably connected with the trainpipe, auxiliary reservoir, 
brake cylinder and pressure-retaining valve, and which 
operates, by variations of the air pressure in the trainpipe, 
(i) to admit air from the auxiliary reservoir (and, when 
required, as will be explained hereafter, from the trainpipe) 
to the brake cylinder, thereby applying the brakes, and at 
the same time to cut off communication from the trainpipe 
to the auxiliary reservoir, and (2) to restore communication 
between the trainpipe and the auxiliary reservoir, and at the 
same time to discharge the air from the brake cylinder to 
the atmosphere, thereby releasing the brakes. 

Tenth — The Hose Couplings, which are attached to 
flexible hose and unite the trainpipe of adjoining vehicles. 

Eleventh — The Pressure- Retaining Valve, which, when 
used, prevents complete discharge of the air from the brake 
cylinder, retaining a pressure of fifteen pounds therein when 
the brakes are released. 

Twelfth — The Automatic Slack Adjuster, which auto- 
matically maintains a constant travel of the piston in the 
brake cylinder, by taking up the slack as the brake shoes 
wear. 

Plate 1 shows the usual arrangement of apparatus and 
piping upon a locomotive and tender, while Plate 2 diagram- 
matically illustrates, in section, the essential parts of the 
brake system and their relative location, as usually applied 
to railroad trains. 

The operations of the brake are controlled by the triple 
valve, the primary parts of which are a piston and slide 
valve. A moderate reduction of air pressure in the train- 
pipe causes the greater pressure remaining stored in the 
auxiliary reservoir to force the piston and its slide valve to 
a position which allows the air in the auxiliary reservoir to 
pass into the brake cylinder and apply the brake ; a sudden 



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WEST1NGH0USE QUlCK-ACTION AUTOMATIC BRAKE. 7 

or violent reduction of the air in the trainpipe produces the 
same effect, but, in addition (if a quick-action triple valve), 
it causes supplemental valves to be opened, permitting the 
air from the trainpipe to also enter the brake cylinder, 
thereby producing a brake-cylinder pressure about 20 per 
cent, greater than that derived from the auxiliary reservoir 
alone and producing a practically instantaneous application 
of the brakes throughout the train. When the pressure in 
the trainpipe is subsequently increased above that remain- 
ing in the auxiliary reservoir, the piston and slide valve are 
forced in the opposite direction to their normal positions, 
thereby restoring communication between the trainpipe and 
the auxiliary reservoir and permitting the air in the brake 
cylinder to escape to the atmosphere through the triple- 
valve exhaust port, connecting pipe, and pressure-retaining 
valve, thus releasing the brakes, and at the same time 
recharging the auxiliary reservoirs. When the pressure- 
retaining valve is in operation, it arrests the discharge to the 
atmosphere when the pressure in the brake cylinder has 
become reduced to fifteen pounds. 

When the engineer wishes to apply the brakes, he 
moves the handle of the engineer's brake valve to the 
right, which cuts off communication with the main reservoir 
and permits a portion of the air in the trainpipe to escape; 
to release the brakes, he moves the handle to the extreme 
left, which allows air to flow from the main reservoir into 
the trainpipe, restoring the pressure therein. 

A device called the Conductor's Valve is placed in 
each passenger car, to which is attached a cord that runs 
throughout the length of the car. By pulling this cord, the 
valve is opened and discharges air from the trainpipe, 
applying the brakes. When the train has been brought to 
a full stop in this manner, the valve must be closed. 



8 WESTINGHOUSE QUICK-ACTION AUTOMATIC BRAKE. 

Should a train break in two, the escape of the air in 
the trainpipe applies the brakes automatically to both sec- 
tions. The brakes are also automatically applied through 
the bursting of a hose or pipe. In fact, any material re- 
duction of pressure in the trainpipe applies the brakes, 
which is the characteristic feature of the Automatic Brake. 

An angle cock is placed in the trainpipe at each end 
of every car, which must be closed before separating the 
couplings to prevent an application of the brakes. A stop 
cock is also placed in the cross-over pipe leading from the 
trainpipe to the quick-action triple valve, and also in the 
trainpipe near the engineer's brake valve, within convenient 
reach of the engineer. The former is for the purpose of 
cutting out, or rendering inoperative, the brake apparatus 
upon a car, if it should become disabled for any reason, and 
the latter is for cutting out the engineer's brake valve upon 
all locomotives except the first, in case two or more are 
attached to the same train. 



PLATE 3. 



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NINE AND ONE-HALF-INCH AIR PUMP. 

(9) 



PLATE 4. 



HMNV.UVE9u.-i~8 




NINE AND ONE-HALF-INCH AIR PUMP. 

(10) 



The Nine and One-half-inch Air Pump* 

The Nine and One-half -inch Air Pump is shown on Plates 
3 and 4. The following description applies to either the 
right or left-hand pump, the only difference between the two 
being in the location of the steam and exhaust connections, 
for convenience of piping. All parts of the two pumps are 
interchangeable. 

As will be seen by examining the Plates, the valve 
gear of the pump consists of pistons 77 and 79, of un- 
equal diameter, connected by rod 76, which imparts the 
movement of the pistons to slide valve 83, and this 
valve in turn controls the steam supply which operates 
main steam piston 65. The reversal of the motion of 
pistons 77 and 79 is controlled by reversing slide valve 
72, the duty of which is to admit and discharge steam to 
and from chamber D, at the right of piston 77. 

Chambers A and C are always in free communication 
through port e, e f . The reversing valve is operated by rod 
71, to which movement is imparted by reversing plate 69, 
which engages reversing button k on the downward stroke 
of the steam piston and shoulder j on the upward stroke. 

Chamber E always communicates with the exhaust in 
order that no back pressure may occur when piston 79 
is forced to the left, and that a partial vacuum shall not 
occur when the piston is drawn to the right. This exhaust 
connection is made by means of port /, shown in the main- 
valve bushing. This port leads from chamber E directly to 
main exhaust port d, so that chamber E, at the left of 
piston 79, is always free from steam pressure. 

When reversing slide valve 72 is in the position shown, 
chamber D is connected, through ports h\ h, reversing- valve 
cavity H, and ports/* and f 1 , with main exhaust passage d, 
d r , d 2 , and there is no pressure at the right of piston 77. 



12 NINE AND ONE-HALF-INCH AIR PUMP. 

As steam enters the pump at X, it passes through pas- 
sage a } a 1 , a 2 into chamber A, between pistons 77 and 79. 
Since the area of piston 77 is greater than that of piston 
79, it is forced to the right, drawing with it piston 79 and 
slide valve 83, to the position shown on Plate 3, thus ad- 
mitting steam below piston 65, through port b, b\ b 2 . 
Piston 65 is thereby forced upward, and the steam above 
piston 65 passes through port c, c 1 , cavity B of slide 
valve 83, port d, and passage d 1 , d 2 , to connection Y, at 
which point it leaves the pump and discharges into the 
atmosphere through the exhaust pipe. 

When piston 65 reaches the upper end of its stroke, 
reversing plate 69 strikes shoulder j on rod 71, forcing 
it and reversing slide valve 72 upward sufficiently to expose 
port g. Steam from chamber C then enters chamber D 
through port^ and port g 1 of the bushing (Plate 4). The 
pressures upon the two faces of piston 79 are thus equal- 
ized, and the piston is balanced. The pressure in cham- 
ber A, acting upon small piston 79, therefore forces it to 
the left, drawing with it piston 77 and slide valve 83. 

With slide valve 83 in its extreme position at the 
left, steam from chamber A is admitted, through port c 1 , c, 
above piston 65, forcing it down ; at the same time, the 
steam below the piston is discharged to the atmosphere 
through port b 2 , b\ b ) chamber B of the slide valve, port 
d, d\ d 2 , and the exhaust pipe connected at Y. 

When piston 65 reaches the lower end of its stroke, 
reversing plate 69 engages reversing button k, drawing it 
and reversing slide valve 72 down to the positions shown, 
and one double stroke of the steam end of the pump has 
been traced. 

The movement of steam piston 65 is imparted to 
air piston 66 by means of the piston rod. As piston 66 is 



NINE AND ONE-HALF-INCH AIR PUMP. 13 

raised, the air above it is compressed, and air from the 
atmosphere is drawn in beneath it ; the reverse is true in 
the downward stroke. 

As piston 66 is raised, the air above it is compressed 
and passes through port r, r 7 , lifts discharge valve 86 
from its seat, as soon as the pressure below the valve is 
greater than the main-reservoir pressure above it, passes 
down into chamber G, and thence into the main reservoir 
through the pipe connected at Z. The upward move- 
ment of the air piston produces a suction which causes 
lower left-hand receiving valve 86 to lift from its seat, 
and atmospheric air enters through strainer W, passes 
to chamber n below the receiving valve, thence past 
that valve into port o, and into the lower end of the air 
cylinder through o 1 , filling the cylinder. In the down- 
ward stroke of the pump, the effect just described is 
produced upon the opposite corresponding receiving and 
discharge valves. 

The receiving and discharge valves of the 9^ -inch 
pump should each have a lift of 3/32 of an inch. 

Directions. 

In starting a pump, always run it slowly until it be- 
comes warm ; by that time, there will be an air cushion in 
the air cylinder and the early steam condensation will have 
escaped through the drain cocks and the exhaust. 

The lubricator should be in operation as soon as 
possible after starting. 

A swab, well oiled, is essential on the piston rod. 
The amount of oil to be used in the steam cylinder of the 
pump depends considerably upon the amount of work per- 
formed : some pumps require more oil than others. Judg- 
ment should determine the amount, it being remembered 



14 NINE AND ONE-HALF-INCH AIR PUMP. 

that a saving of ten cents' worth of oil may result in a 
dollar's worth of wear of the pump. 

Engine oil should never be used in the air cylinder, as 
it eventually clogs and restricts the air passages, causing the 
pump to heat and producing bad results in general ; valve 
oil gives the best performance. The air cylinders of pumps 
in heavy service should receive a small amount of oil each 
trip, and continuous or regular oiling will give the best 
results. 

It is an aid to good operation to run a hot solution of 
potash through the air cylinder three or four times a year. 
This should always be followed by considerable clean, hot 
water, and the union should be disconnected at the main 
reservoir to prevent the potash from working back into the 
brake system, where it would destroy gaskets. 



The Eight-inch Air Pump. 

Plate 5 shows the Eight-inch Air Pump in its upward 
stroke. 10 is the steam piston and rod ; 1 1, the air piston ; 
and piston valves 7, piston 23, reversing slide valve 16, 
reversing rod 17 and reversing plate 18 constitute the 
valve gear of the pump. Valves 30 and 32 are the dis- 
charge air valves, and 33 and 31 are the receiving air 
valves. 

In service, the pump governor is attached at X and 
has a suitable pipe connection with the steam supply. 
Steam enters chamber m, and port k> always uniting 
chambers 7n and ^, conducts steam from the former to the 
latter, which contains the reversing valve. 

When reversing slide valve 16 is in the position 
shown, steam passes from chamber m, through port h, into 
chamber e, and thence through port a into chamber d above 
reversing piston 23. The same steam pressure now 
acts downward upon piston 23 and lower piston valve 7, and 
upward on upper piston valve 7 ; but, as the combined 
areas of piston 23 and lower piston valve 7 are greater 
than that of upper piston valve 7, the steam forces piston 
23 and piston valves 7 downward to the position shown. 
Steam is admitted to the cylinder through the upper ports 
in bushing 26, raising piston 10, while the steam above 
piston 10 passes through the upper ports in bushing 25, 
thence through port/, /, shown by dotted lines, into cham- 
ber £*, and out at Y, through a suitable pipe, to the smoke 
arch, where it is discharged to the atmosphere. 

When piston 10 has nearly completed its upward 
stroke, reversing plate 18 engages shoulder ?i and 
raises reversing slide valve 16 to its uppermost posi- 
tion, in which port a is closed and, as the cavity in the 
valve connects ports b and c, the steam above piston 23 is 

(15) 



PLATE 5. 




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52 trj 52 5ss?« 

5a 



EIGHT-INCH AIR PUMP, 

(16) 



EIGHT-INCH AIR PUMP. 17 

discharged through port b, the cavity in reversing slide 
valve 16, port c, and port/", f into chamber £-, and thence 
to the atmosphere through the exhaust pipe at Y. 

There being now no pressure in chamber d to act down- 
ward upon piston 23, the upward force upon large piston 
valve 7 overbalances the downward force upon smaller pis- 
ton valve 7 and both are raised so as to close the upper ports 
and uncover the lower ports in both bushings 25 and 26. 
Steam from chamber 771 is admitted through the lower ports 
of bushing 25 into the chamber above piston 10, forcing it 
down, and the steam below the piston is discharged through 
the lower ports in bushing 26 and the passage f 1 ,/ 1 into 
chamber g, and out through the exhaust pipe at Y. 

When piston 10 has nearly completed its downward 
stroke, the lower face of reversing plate 18 engages the 
button at the end of reversing rod 17, drawing the revers- 
ing slide valve down to the position shown, and the motion 
of the pump is again reversed. 

During the upward stroke of the pump, the air above 
piston 1 1 is compressed and discharged through port P into 
the space between receiving valve 31 and discharge valve 
30, forcing the latter from its seat and flowing through 
chamber t and port r into chamber s, and out at Z to the 
main reservoir. The main-reservoir pressure in chamber ,y 
holds lower discharge valve 32 upon its seat during the 
upward stroke of the pump, and the tendency toward a 
vacuum below piston 11 allows receiving valve 33 to be 
forced from its seat by atmospheric pressure, which then 
enters into the lower part of the air cylinder. In the down- 
ward stroke of the pump, the conditions are reversed : 
receiving valve 31 is lifted to fill the chamber above piston 
II as it descends, and the air compressed below the piston 



l8 EIGHT-INCH AIR PUMP. 

forces discharge valve 32 from its seat and flows through 
chamber s and the pipe connected at Z to the main reservoir. 

The receiving valves should have a lift of }i of an 
inch, and the discharge valves, 3/32 of an inch. 

Recommendations concerning the care of the Nine and 
One-half-inch Pump apply also to the Eight-inch Pump. 



The Air-Pump Governor* 

The location of the Air- Pump Governor (Plate 6) in 
the brake system is illustrated on Plate 2. 

The purpose of the governor is to cut off the steam 
supply, and thus practically stop the pump, when the 
desired air pressure has been attained. The air pressure 
connection to the governor is at W. The adjustment of the 
governor is accomplished by means of adjusting nut 40, 
which regulates the tension of spring 41 upon diaphragm 42. 
While the tension of spring 41 is more than sufficient to 
withstand the air pressure in chamber a upon the diaphragm, 
it holds the small pin valve upon its seat; but, when the air 
pressure upon diaphragm 42 becomes greater than the 
tension of spring 41, the diaphragm is thereby raised, un- 
seating the small pin valve. Air from chamber a then 
flows into the chamber above piston 28 and forces it down, 
thereby seating steam valve 26 and cutting off the steam 
supply to the pump. 

Whenever the air pressure becomes reduced, by leak- 
age or otherwise, spring 41 forces diaphragm 42 down and 
the pin valve is again seated: the air in the chamber above 
piston 28 then escapes to the atmosphere through the small 
relief port c, and spring 31, assisted by the steam pres- 
sure below valve 26, raises piston 28 to its normal position, 
shown in the cut, and the pump resumes operation. 

During the time that the pin valve is unseated, there 
is a continuous escape of air to the atmosphere through 
relief port c. This leakage, in conjunction with the leakage 
of steam through a small port (indicated by dotted lines) 
through steam valve 26, serves to keep the pump slowly 
operating to avoid trouble from steam condensation that 
might otherwise accumulate. 

(19) 



PLATE 6. 




PUMP GOVERNOR, 

(20) 



PUMP GOVERNOR. 21 

35 is a drip-pipe connection to the chamber imme- 
diately below piston 28. Its purpose is to permit any steam 
that may leak past the stem of valve 26, or any air that may 
leak past piston 28, to escape to the atmosphere. To avoid 
freezing, the connecting drip pipe should be made as short 
as the accomplishment of its purpose will permit. 

The description of the operation of this governor 
applies also to that of the double, or " Siamese," Governor 
used with the High-Speed and High-Pressure Control 
Equipments, which has two diaphragm portions of the gov- 
ernor connected to one steam-valve cylinder ; but only one 
diaphragm is at any one time operative upon the lower 
portion of the governor. 



The Main Reservoir* 

The principal object of the Main Reservoir is to store 
an abundant air supply for the purpose of releasing and 
quickly recharging the brakes; but it also serves to entrap 
any dirt and water suspended in the compressed air, and to 
thereby prevent their being conveyed into the brake system. 

The Main Reservoir should have a capacity of not less 
than 20,000 cubic inches (and often more) upon passenger 
engines, and not less than 40,000 cubic inches on freight 
engines — 50,000 is better. The use of a large reservoir in 
freight service is of great benefit to the air pump, as it 
permits a sufficient volume of air to be compressed, while 
the brakes are applied, to release the brakes and recharge 
the auxiliary reservoirs without running the pump at a high 
rate of speed for that purpose, which would entail liability 
of its overheating. 

If possible, the location of the Main Reservoir should 
always be such that the dirt, oil, and moisture in the com- 
pressed air will drain into it ; but location is a considera- 
tion subordinate to that of sufficient capacity. In order to 
secure sufficient capacity, it is necessary, in some cases, to 
locate the Main Reservoir at the back of the tender : this 
practice necessitates two additional lines of hose between 
the engine and tender, which form pockets in which water 
precipitated from the compressed air may collect, and in 
winter freeze, and where oil may accumulate and rapidly 
deteriorate the hose. The plan is also generally expensive. 
The best location for the Main Reservoir is back of the cylin- 
der saddle, between the frames, or under the runningboards: 
it is often found necessary to locate them under the cab 
footboards. 

The use of two Main Reservoirs is very advantageous, 
in providing superior facilities for the condensation and 

(22) 



MAIN RESERVOIR. 23 

precipitation of moisture and the deposit of oil and other 
foreign matter. The compressed air from the pump should 
be delivered into one and piped to the brake valve from the 
other, the two being connected by suitable piping. The 
points at which the air enters and leaves each reservoir 
should be as far separated as possible. 

Main Reservoirs should always be drained after each 
trip, the drain cock being left open during the interval 
between trips, in order to completely remove oil and water 
from the space provided for storing air. A reservoir partly 
filled with water is correspondingly reduced in capacity, 
which is apt to be accompanied by defective release and 
slow recharging of the brakes and by a hot pump ; and the 
water is likely to work back and accumulate in hose and 
sags in the trainpipe, as well as in the triple valves, where 
it may freeze and cause serious trouble in winter. 



The " G-6 " Engineers Brake Valve. 

The "D-5," "E-6 ,? and " F-6 " Brake Valves are 
practically identical ; the different letters and figures simply 
refer to the same valve, as illustrated in different Cata- 
logues. The ' ' G-6 ' ' Valve is also the same, except that the 
Slide-Valve Feed Valve supplants the former Feed- Valve 
Attachment. 

Before describing the operation of the Brake Valve, it 
is advantageous to explain a few commonly used terms, which 
are as follows : 

Excess Pressure — The difference between the pres- 
sure in the main reservoir and that in the trainpipe ; this, 
when the train brake apparatus is fully charged, is usually 
from 20 to 30 pounds. Excess pressure combines with 
abundant main-reservoir capacity to insure prompt release 
and recharging. The amount of excess pressure to be carried 
is determined by the character of the road, length of train, 
size of main reservoir, and kindred considerations. 

Service Application — A gradual application of the 
brakes, such as is usual in slowing up or in a station stop : 
a gradual reduction of trainpipe pressure produces this 
effect. 

Emergency Application — Is one in which the full 
braking power is applied almost instantaneously, for the 
purpose of avoiding a wreck, saving lives, etc. : a sudden 
reduction of trainpipe pressure produces this effect. 

The red-hand gauge connection is piped to R (Plates 
7 and 8), and indicates main-reservoir pressure. A tee is 
usually inserted in this pipe for a pipe connection to the 
pump governor, which is generally adjusted to cut off the 
steam supply when main-reservoir pressure has reached 90 
pounds. The black-hand gauge connection is piped to W 
and is directly connected to the equalizing reservoir; but, as 

C 24 ) 



"g-6" engineer's brake valve. 25 

will presently be explained, the black hand also indicates 
trainpipe pressure. The black hand is usually referred to 
as the trainpipe-pressure hand, and the red, as the main- 
reservoir-pressure hand. 

The customary standard trainpipe pressure is 70 
pounds, while 90 pounds is quite general as a standard 
main-reservoir pressure ; but these pressures may be modi- 
fied to meet special conditions. In this book, 70 pounds 
will be considered the standard trainpipe, and 90 pounds, 
the standard main-reservoir pressure ; but it should be 
understood that, in special cases, it is proper to modify 
this practice. 

There are five different positions of the Brake Valve 
handle; namely, Release, Running, Lap. Service Applica- 
tion and Emergency Application Positions. As the engi- 
neer faces the valve, the position farthest to his left is 
Release, and the other positions follow to the right in the 
order named. 

Release Position — The purpose of this position is 
to provide a large and direct passage from the main reser- 
voir to the trainpipe, to permit a rapid flow of air into 
the latter, to insure a quick release and recharging of the 
brakes. Release is the position shown on Plates 7 and 
8. Referring to Plate 2, it will be seen that a pipe leads 
from the main reservoir to the Brake Valve. It is connec- 
ted at X (Plate 7), and, when the Brake Valve is in Re- 
lease Position, main-reservoir air flows through passage A, 
A to the chamber above rotary valve 14, thence through 
port a in that valve, cavity b in its seat 3, cavity c in the 
valve (which overlaps cavity 6) and passage /, I 1 to the 
trainpipe at Y. Port^-, being then also exposed to cavity 
c, simultaneously conducts air into chamber D above equali- 
zing piston 18. Chamber D is, by means of passage S, S 



26 "g-6" engineer's brake valve. 

and a pipe connected at T, always in open communication 
with the equalizing reservoir, shown on Plate 2. Port J of 
the rotary valve registers with port e in its seat, and air is 
also conducted through these ports to chamber D. It thus 
occurs that, in Release Position, two small ports feed the 
equalizing reservoir and one large one supplies the trainpipe. 

The purpose of the equalizing reservoir is to increase 
the volume of chamber D above piston 18. Without this 
reservoir, the volume would be so small that a desired re- 
duction of pressure could be made only with difficulty, and 
the equalizing piston cculd not be depended upon to oper- 
ate in a manner to cause the proper action of the brakes. 

While the handle of the Brake Valve is in Release 
Position, " warning port'' r (shown in dotted lines), of 
very small area, discharges main-reservoir pressure to 
the atmosphere with considerable noise, attracting the 
engineer's attention if he subsequently neglect to move the 
valve handle to Running Position. If the Brake Valve were 
allowed to remain in Release Position, a pressure of 90 
pounds would result, not only in the main reservoir, but 
also in the equalizing reservoir, trainpipe, and auxiliary res- 
ervoirs, since, in this position, they are all in direct commu- 
nication. To stop the escape of air through the ' ' warning 
port" and to prevent overcharging the brake system, the 
valve handle is moved to Running Position. 

Running Position — This is the proper position of the 
Brake Valve when when the brake apparatus is charged and 
ready for an application. In this position (shown on Plate 
9), the main-reservoir pressure attains the proper excess 
above that in the trainpipe. Main -reservoir air, which 
is always present in the chamber above rotary valve 14, is 
conducted by port j in that valve and passages f and f 1 
into chamber F (Plate 8); thence, as hereafter explained, 



PLATE 7. 




f PI PI TAPy 7" A. 

"G-6" ENGINEER'S BRAKE VALVE. 



(27) 



PLATE 8. 




To Gauge 

— BLACK HAND — 

Train Pipe Pressure 



"G-6" ENGINEER'S BRAKE VALVE. 



( 28) 



PLATE 9< 




"G-6" ENGINEER'S BRAKE VALVE, 



(29) 



30 "g-6" engineer's brake valve. 

its course is through the Feed Valve, from which it is con- 
ducted by passages z, /and I 1 (Plate 7) into the trainpipe 
at Y. Port g still connects chamber D with cavity c of the 
rotary valve, and, as cavity c still overlaps passage /, the 
equalizing reservoir and trainpipe are directly connected ; 
the same pressure consequently exists above and below 
equalizing piston 18. The Feed Valve is adjusted to cut 
off the air supply to the trainpipe when the pressure reaches 
70 pounds, so that charging then ceases, though the pump 
governor will not stop the pump until main-reservoir 
pressure has reached 90 pounds. 

The operation of the Feed Valve is described hereafter. 

Lap Position — This position, the second from Re- 
lease, is that in which all ports are operatively blanked. 
After the preliminary discharge of air for a service applica- 
tion of the brakes, the valve handle is placed in this position 
until it is desired to make a futher trainpipe reduction or to 
release the brakes. If the pump be started with the Brake 
Valve " on lap," the result will be a pressure of 90 pounds 
in the main reservoir and no pressure in the trainpipe, when 
the pump is stopped by the Governor. 

Service Application Position — This position is the 
third from Release, and is used to cause the service appli- 
cation, as already described. A groove in the lower face 
of rotary valve 14 connects port ^with grooved in its seat, 
causing air to be discharged from chamber D and the equaliz- 
ing reservoir, through port k, into the atmosphere, thus 
reducing the pressure above piston 18. The greater pres- 
sure in the trainpipe below the piston thereupon forces it 
upward and unseats the attached discharge valve, and train- 
pipe air discharges, through port m and passages n and n 1 
of exhaust fitting 22, into the atmosphere. The desired 
reduction of pressure in chamber D having been secured, 



"g-6" engineer's brake valve. 31 

the handle of the valve is moved back to Lap Position. 
It is to be observed, however, that, after the handle of the 
valve has been moved to this position, air will contimie to 
discharge from exhaust fitting 22, until the pressure in the 
trainpipe has been reduced to a trifle less than that in 
chamber D and the connected equalizing reservoir; then 
piston 18 automatically forces the discharge valve to its seat, 
through the action of the greater pressure upon its upper 
surface. Ordinarily, a reduction of from 5 to 8 pounds in 
trainpipe pressure is sufficient for an initial application of 
the brakes. 

Emergency Application Position — This position, 
which is the farthest from Release, is used for an emergency 
application of the brakes. ' ' Direct - application - and - 
exhaust-port ' ' k and ' ' direct-application-and-supply-port ' ' 
/ (Plate 8) are directly connected by means of large cavity 
c in rotary valve 14, which, in this position, overlaps both, 
thus permitting a very rapid discharge of trainpipe air 
through large ports. The resulting sudden reduction of 
trainpipe pressure causes the nearly instantaneous applica- 
tion of the brakes throughout the train, as already described. 



The Slide- Valve Feed Valve* 

Plates 10 and n illustrate the device known as the 
Slide- Valve Feed Valve, which may be used with either the 
' ' D-5, " " E-6, " ' ' F-6 " or ' < G-6 ' ' Brake Valve, to main- 
tain a predetermined trainpipe pressure while the brake- 
valve handle is in Running Position. 

Plate 10 is a central section through the supply- valve 
case and governing device, and Plate 1 1 is a central section 
through the regulating valve and spring box and a trans- 
verse section through the supply- valve case. 

Ports f 1 and i register with ports in the Brake Valve, 
designated by similar letters on Plate 8, and, in Running 
Position, main-reservoir pressure constantly has free access, 
through passages/*' and/", to chamber F. Chamber E, which 
is separated from chamber F by supply-valve piston 54, 
is connected with passage /, and thus with the trainpipe, 
through passage c, c, port a (controlled by regulating 
valve 59) and chamber G, under diaphragm 57. Regula- 
ting valve 59 is normally held open by diaphragm 57 and 
regulating spring 67, the tension of which is adjusted by 
regulating nut 65. When so open, chamber E is in com- 
munication with the trainpipe and is subject to trainpipe 
pressure. 

When the handle of the Engineer's Brake Valve is placed 
in Running Position, air pressure from the main-reservoir 
in chamber F forces supply-valve piston 54 forward, com- 
pressing its spring 58, carrying supply valve 55 with it and 
uncovering port &, and thereby gains entrance directly into 
the trainpipe through passage z, i. The resulting increase of 
pressure in the trainpipe (and so in chamber G under dia- 
phragm 57) continues until it becomes sufficient to overcome 
the tension of regulating spring 67, previously adjusted to 
yield at 70 pounds. Diaphragm 57 then yields and allows 

(3O 



PLATE 10. 



51 




SLIDE-VALVE FEED VALVE, 



(33) 



PLATE ii. 




63 62 65 

SLIDE-VALVE FEED VALVE. 



(34) 



SLIDE-VALVE FEED VALVE. 35 

regulating valve 59 to be seated by spring 60, closing port a 
and cutting off all communication between chamber E and 
the trainpipe. The pressures in chambers F and E then 
become equalized, through leakage past supply-valve 
piston 54, and supply-valve-piston spring 58, previously 
compressed by the relatively high pressure in cham- 
ber F, now reacts and forces supply valve 55 to its normal 
position, closing port b and cutting off communication be- 
tween the main reservoir and the trainpipe. A subsequent 
reduction of trainpipe pressure reduces the pressure in cham- 
ber G and permits regulating spring 67 to force regulating 
valve 59 from its seat, thereby causing the accumulated 
pressure in chamber E to discharge into the trainpipe. The 
equilibrium of pressure upon the opposite faces of supply- 
valve piston 54 being thus destroyed, the higher main- 
reservoir pressure in chamber F again forces it, with supply 
valve 55, forward and recharges the trainpipe through port 
b, as before. 



PLATE 12. 




OLD-STYLE FEED VALVE. 

(36) 



The Old-Style Feed Valve. 

The accompanying cut (Plate 12) illustrates what is 
now usually known as the Old-Style Feed Valve. It was 
used with the "D-5," "E-6" and "F-6" Brake Valves to 
maintain a pressure of 70 pounds in the trainpipe when 
the brake valve was in Running- Position. 

When connected to the brake valve, passage f 1 regis- 
ters with passage/ 7 of the brake valve (Plate 8), and 
passage i registers with passage i of the brake valve, which 
passage is connected with the trainpipe by means of passage 
/, l 1 (Plate 7), into which it leads. 

Piston 45 of the Feed Valve is subject to the upward 
pressure of regulating spring 39 and to the downward 
air pressure in chamber B above the piston. The tension 
of spring 39 is so adjusted, by regulating nut 41, that a 
pressure of 70 pounds (or other desired trainpipe pressure) 
is necessary in chamber B to overcome it and force the piston 
down. An upward movement of the piston unseats supply 
valve 34 and a downward movement permits spring 35 to 
seat it. Chamber B always contains the same pressure as 
that which exists in the trainpipe, being in open communi- 
cation therewith. 

When the brake valve is in Running Position and the 
pressure in chamber B is less than 70 pounds, regulating 
spring 39 will raise piston 45 and unseat supply valve 34. 
Air from the main reservoir, coming through passage f,/ 1 
of the brake valve, enters the Feed Valve passage/* 7 , passes 
supply valve 34 into chamber B, and thence discharges, 
through passage i and the corresponding passage i in the 
brake valve, into the trainpipe. When the pressure in the 
trainpipe and chamber B becomes 70 pounds, it overcomes 
the tension of regulating spring 39 and forces piston 45 
downward, allowing spring 35 to seat supply valve 34. No 

(37) 



3& OLD-STYLE FEED VALVfi. 

further movement of air can take place through the Feed 
Valve until the pressure in chamber B and the trainpipe 
becomes, by leakage or otherwise, so reduced that the 
regulating spring can again force the piston upward and 
unseat the supply valve. 



The "D-8" Engineer's Brake Valve. 

What has been said concerning the ' 'G-6' ' Brake Valve, 
defining- such terms as Excess Pressure, Service Applica- 
tion, Emergency Application and the usual trainpipe and 
main-reservoir pressures, as well as the description relating 
to the different positions of the brake-valve handle, applies 
also to the " D-8 " Brake Valve. 

Plates 13 and 15 are sectional views of the Brake Valve 
in the Release Position; Plate 14 is a plan view of the 
rotary-valve seat, and Plate 16 illustrates the rotary valve 
and seat in perspective. 

A pipe connected at R (Plates 13 and 14) leads to the 
red-hand connection of the air gauge ; a pipe from W leads to 
the black-hand connection ; the pipe secured at T leads to 
the equalizing reservoir (Plate 2), and the pipe from V 
connects the trainpipe with the pump governor. The train- 
pipe is connected at Y and air from the main-reservoir 
enters the Brake Valve at X and always has access to the 
chamber above rotary valve 13 ; its further course de- 
pends upon the position of the rotary ralve. 

Release Position — In the Release Position of the 
Brake Valve, main-reservoir air is conducted to the train- 
pipe at Y by supply port a in rotary valve 13, cavity b in 
its seat, cavity c (which overlaps both cavity b and passage 
/ in this position) and passage /. Port/ of the rotary valve 
registers with port e in the valve seat, so that chamber D, 
above equalizing piston 17, and the equalizing reservoir 
(connected therewith through port S and the pipe secured 
at T) are in direct communication with the main reservoir. 
Equalizing port^* (shown by dotted lines on Plate 15) is in 
communication with cavity c of the rotary valve, so that 
chamber D is also fed through this port. 

(39) 



PLATE 13. 




"D-8" ENGINEER'S BRAKE VALVE. 



(40) 



PLATE 14. 



1-P06IT.'0N F-OR/JRfl/EASCNG- BflAKt) 




24-— "To Small REsenvom 



D-8" ENGINEER'S BRAKE VALVE. 



(41) 



42 "D-8 ENGINEER S BRAKE VALVE. 

If the brake-valve handle were allowed to remain in 
Release Position, a pressure of 70 pounds would exist 
in the main reservoir and throughout the brake system 
when steam is finally cut off from the pump by its govern- 
or. This occurs because the pump governor is piped to 
the trainpipe and is therefore adjusted to cut off the steam 
supply as soon as the full trainpipe pressure of 70 pounds 
has been secured. To obtain excess pressure in the main 
reservoir, the brake-valve handle must therefore be moved 
into Running Position. 

Running Position — In this Position, port j of the 
rotary valve registers with passage f leading to excess- 
pressure valve 2 1 , held to its seat by excess-pressure spring 
20, the tension of which is equal to a pressure of 20 pounds 
per square inch. Air from the main-reservoir flows through 
port/ into passage/*, where it encounters the excess-pres- 
sure valve, forced toward its seat by trainpipe pressure and 
spring 20. When the pressure in passage/" exceeds that in 
the trainpipe by more than 20 pounds, the excess-pressure 
valve is thereby forced from its seat, compressing spring 
20, and the air flows through passages f 1 and / into the 
trainpipe, as shown on Plate 13. Port^, leading through 
the rotary-valve seat to chamber D, still communicates 
with cavity c, which also overlaps passage /, causing equali- 
zation of pressure in the trainpipe and chamber D — the 
latter being connected with the equalizing reservoir, as 
already explained. With the brake-valve handle in Running 
Position, the pump governor will cut off the steam supply 
when trainpipe pressure has become 70 pounds ; but the 
interposition of the excess-pressure valve has caused 
a pressure, 20 pounds in excess of that in the trainpipe, to 
accumulate in the main reservoir, so that the main-reservoir 
pressure is 90 pounds. 



"d-8" engineer's brake valve. 43 

Lap Position — When the rotary valve is in the Lap 
Position, all ports are operatively blanked. If the pump be 
started with the valve in this position, no air can reach the 
trainpipe to operate the pump governor, and the pump will 
not stop until the main-reservoir pressure has become about 
equal to the steam pressure in the boiler. 

Service Application Position — In this position, 
communication between the main reservoir and the train- 
pipe, and between the trainpipe and chamber D, is cut off, 
and cavity/ in the lower face of the rotary valve connects 
port e with the small preliminary exhaust port h, whereby 
air is discharged from chamber D into the atmosphere. The 
resulting reduced pressure in chamber Dand the equalizing 
reservoir permits the greater trainpipe pressure below 
equalizing piston 17 to raise it, unseating the trainpipe 
discharge valve ; trainpipe air thereupon discharges through 
passage n into the atmosphere, until the pressure becomes 
a trifle less than that remaining in chamber D, when the 
piston is forced downward and reseats the valve. 

Emergency Application Position — In this position, 
cavity c of rotary valve 13 overlaps both the large ' 'direct-ap- 
plication-and-supply-port" / and "direet-application-and- 
exhaust-port' ' k ; a large, direct avenue is thus provided for 
quickly discharging trainpipe air into the atmosphere, and 
the resulting sudden reduction of trainpipe pressure causes 
an emergency application of the brakes. 

Port e is slotted to the right ; this slot is provided in 
order that there may be no position between Release and 
Running Positions in which communication between the 
main-reservoir and the trainpipe is wholly cut off. If the 
rotary valve be so moved that port/ is above the space be- 
tween ports e and/", main-reservoir air can still feed through 
the slotted port into chamber D, thence through port g into 



PLATE 1 5< 




D-8" ENGINEER'S BRAKE VALVE. 



(44) 



PLATE 16. 




"D-8" ENGINEER'S BRAKE VALVE. 
Release Position. 



(45) 



46 "d-8" engineer's brake valve. 

cavity c of the rotary valve and through passage / into the 
trainpipe at Y. Port e also serves to allow main-reservoir 
pressure to reach chamber D above the equalizing piston 
when the valve handle is being moved to Release Position ; 
this connection is established as soon as port j in the 
rotary- valve comes into register with slotted port e in the 
rotary-valve seat. 



The Quick-Action Triple Valve* 

The Quick-Action Triple Valve is located in the brake 
system as shown on Plate 2. 

This valve receives its name from the three distinct 
operations it performs in response to variations of train- 
pipe and auxiliary-reservoir pressures : it ( 1 ) charges the 
auxiliary reservoir, and (2) applies and (3) releases the 
brakes. The various positions of the working parts of the 
triple valve, in accomplishing these results, are illustrated in 
Figs. 1, 2, 3 and 4, Plate 17, while Fig. 5 is a perspective 
view of the slide valve and its seat. 

The various parts of the triple valve, as shown 
on Plate 17, are 2, triple-valve body ; 3, slide valve ; 
4, main piston ; 5, piston packing ring ; 6, slide-valve 
spring ; 7, graduating valve ; 8, emergency piston ; 
9, emergency-valve seat; 10, emergency valve; 11, 
emergency-valve rubber seat ; 12, check-valve spring ; 
13, check-valve case ; 14, check-valve-case gasket ; 15, 
check valve ; 16, strainer ; 19, cylinder cap ; 20, gradu- 
ating-stem nut; 21, graduating stem ; 22, graduating spring; 
23, cylinder-cap gasket; 28, emergency-valve nut; and i 
and k, the feed grooves. 

Strainer 16 is designed to exclude foreign matter from 
the triple valve. Piston 4 operates, in response to varia- 
tions of trainpipe and auxiliary-reservoir pressures, to open 
and close feed groove /, and controls the movements of 
the slide valve and the graduating valve. The latter is 
secured to the piston stem by a pin, shown in dotted lines. 

The graduating valve, moved by the main piston, 
controls the flow of air from the auxiliary-reservoir through 
service ports ports H^and Zof the slide valve. 

The slide valve, moved by the main piston, controls 
communication between the brake cylinder and the atmos- 

(47) 



48 QUICK-ACTION TRIPLE VALVE. 

phere, between the auxiliary reservoir and the brake cylin- 
der, and also between the auxiliary reservoir and the cham- 
ber above emergency piston 8. 

Charging. 

Air from the trainpipe enters the triple valve at A 
(Fig. i) and flows through passages e,f, g and h, past 
the main piston through feed grooves i in the bushing 
and k in the piston seat, and thence through chamber m 
to the auxiliary reservoir, as indicated. Air continues to 
flow from the trainpipe to the auxiliary reservoir until the 
pressures equalize, when the main piston is balanced. The 
main piston constitutes a movable partition wall, separating 
trainpipe and auxiliary-reservoir pressures, and, in studying 
the operation of the triple valve under various conditions, 
the first essential consideration is always as to which face 
of the main piston is exposed to the greater pressure : this 
determines the direction in which it will move. 70 pounds 
is the usual trainpipe pressure, acting upon both faces of 
the main piston when the trainpipe and auxiliary reservoirs 
are fully charged. 

Service Application. 

To apply brakes for a service stop, a gradual reduc- 
tion of trainpipe pressure is necessary ; and, for the pur- 
pose of illustration, the first reduction will be assumed to be 
one of five pounds, thus leaving a pressure of 65 pounds to 
act upon the trainpipe face of the main piston, while the origi- 
nal 70 pounds still operates upon the auxiliary-reservoir face. 
As a result of this reduction, the greater auxiliary-reservoir 
pressure forces the main piston to the left (Fig. 2). As the 
piston moves, it closes feed groove i, cutting off communi- 
cation between the trainpipe and the auxiliary reservoir, and 
unseats graduating valve 7, establishing communication 



QUICK-ACTION TRIPLE VALVE. 49 

between transverse passage W and port Z of the slide 
valve. When the graduating valve has become unseated, 
the collar at the end of the piston stem engages the slide 
valve, which is then also drawn to the left in the further 
movement of the piston, thereby cutting off communication 
between exhaust cavity n in the slide valve and passage r 
leading to the brake cylinder. The movement of the main 
piston to the left is arrested by contact of its stem j with 
graduating stem 21, held in position by graduating spring 
22. In this position, port Z in the slide valve registers 
with port r, and auxiliary reservoir air flows through ports 
W and Z of the slide valve and passage r to the brake 
cylinder at C. When the auxiliary-reservoir pressure has 
become, through expansion into the brake cylinder, slightly 
less than that (65 pounds) upon the trainpipe face of the 
main piston, the greater trainpipe pressure forces the piston 
back sufficiently to seat the graduating valve, as shown 
in Fig. 3. This is known as the li lap " position. 

If it be subsequently desired to apply the brake with 
greater force, a further trainpipe reduction is made, which 
again leaves auxiliary-reservoir pressure in excess of that 
in the trainpipe, whereby it again forces the main piston 
to the left and unseats graduating valve 7, the slide valve 
not moving. A corresponding further reduction of auxil- 
iary-reservoir pressure results, through discharge of air into 
the brake cylinder. Such trainpipe reductions may be 
repeated until the auxiliary-reservoir and brake-cylinder 
pressures have finally equalized : the brake is then fully 
applied, and any further trainpipe reduction is but a waste 
of trainpipe air. A total reduction of about 20 pounds 
causes the auxiliary-reservoir and brake-cylinder pressures 
to equalize. 



50 QUICK-ACTION TRIPLE VALVE. 

Release. 

To release the brake, the engineer admits the ex- 
cess pressure of the main reservoir into the trainpipe, 
thus increasing the pressure upon the trainpipe face of the 
main piston until it becomes greater than that upon the 
auxiliary-reservoir face and thereby forcing the piston to 
its position at the extreme right, as shown in Fig. i. In 
this position, the air in the brake cylinder is discharged 
through passage r, exhaust cavity n in the slide valve, 
and passage^ into atmosphere, either directly or through 
the pressure-retaining valve, where employed. Feed 
groove i being again uncovered in this position of the 
piston, the auxiliary reservoir becomes recharged with air 
from the trainpipe. 

Emergency Application. 

A gradual reduction of trainpipe pressure causes the 
main piston to move to the left until stem j encounters 
stem 21, when the tension of the graduating spring pre- 
vents further movement ; but a sudden trainpipe reduction 
causes the main piston to move out so quickly that grad- 
uating spring 22 cannot withstand the impact of stemy, but 
yields so that the piston moves to the position shown in 
Fig. 4. In this position of the parts, a diagonal slot in 
the slide valve (shown in Fig. 5) uncovers port t (indi- 
cated by the dotted lines just below the letter Z), which 
admits air from the slide-valve chamber to the chamber 
above emergency piston 8. Piston 8 is thereby forced 
downward and unseats emergency valve 10, allowing the 
pressure in the small chamber Y above check valve 15 to 
escape into the brake cylinder. Trainpipe pressure in- 
stantly raises the check valve and trainpipe air rushes 
through chambers a, Fand X into the brake cylinder at 












~z: 



TO AUXt 

res'r! 



30 



TO BRAKE 

crCo. 



m 



14 



PLATE 17 




Fig. i.— Release Position 




Fig. 3.— Lap Position 




Fig. 4.— Emergency Application 



QUICK-ACTION TRIPLE VALVE. 



QUICK-ACTION TRIPLE VALVE. 5 1 

C. Air from the auxiliary reservoir simultaneously flows 
through port k? of the slide valve and passage r into the 
brake cylinder ; but, port 6* being very small in compari- 
son with the passageway through chambers a, Kand X y 
very little auxiliary-reservoir air reaches the brake cylinder 
before the trainpipe discharge thereto is completed. It 
thus occurs that, in an emergency application, an increased 
brake-cylinder pressure is secured through the presence of 
the air supplied by the trainpipe in addition to that from 
the auxiliary reservoir, which is the only source of air 
pressure for the brake cylinder in service applications of 
the brakes. 

The rapid discharge of air from the trainpipe into the 
brake cylinder, in the manner just described, causes a 
sudden reduction of trainpipe pressure, which causes a 
similar operation of the triple valve upon the next car ; 
the operation of that valve similarly affects the next, and 
so on, serially, throughout the train. 

The release is accomplished in the same manner as 
that after a service application. 



The Plain Triple Valve* 

The Plain Triple Valve is illustrated on Plate 18, and 
its location in the brake system is indicated on Plate 2. 

In a service application, the operation of the plain triple 
valve is precisely the same as that of the quick-action 
valve, already described, and the operating parts involved 
are, in all essential respects, identical. The absence of the 
emergency-valve mechanism, through which quick serial 
operation and a relatively higher brake-cylinder pressure 
are secured by the quick-action valve, is the essential dif- 
ference in the structures. 

It will be observed that the slide valve of the plain 
triple valve is shorter than that of the quick-action triple 
valve : this is explained in describing the emergency appli- 
cation of the brake. Upon a sudden reduction of trainpipe 
pressure, the piston strikes the graduating stem, compresses 
its spring, and moves to its extreme downward position. 
In this position, the upper edge of the slide valve is below 
the lower edge of the service port in the slide-valve bush- 
ing, and unobstructed communication between the auxiliary 
reservoir and the brake cylinder is secured through compar- 
atively large ports. Instead of passing through the slide 
valve passages, as in a service application, the air from the 
auxiliary reservoir, entering the triple valve through a pipe 
connected at B, discharges directly into the brake cylinder 
through port r. In an emergency application, therefore, 
the less restricted passages cause the full brake-cylinder 
pressure to occur more promptly ; but the absence of the 
emergency valve in the structure of the plain triple valve 
results in no quick serial action from car to car and in no 
greater final brake-cylinder pressure than may occur in a 
service application. 

It will be further observed that the plain triple valve 

( 52) 



PLATE 18. 




PLAIN TRIPLE VALVE. 

(53) 



54 PLAIN TRIPLE VALVE. 

of Plate 1 8 has not the familiar four-way cock ; the triple 
valve is the same, however, aside from the elimination of 
this part, which came into use at a time, long passed, 
when there were many straight-air brakes in service. At 
that time, if there were many straight-air brakes in a train, 
any automatic brakes in the train could be transformed 
into the straight-air brake by means of this cock. When 
the straight-air brake disappeared, a lug was so added to 
the four-way-cock handle that, while the brake could be cut 
out of service, if necessary, by means of the cock, it could 
no longer be converted into the straight-air brake. A fur- 
ther step has now been taken and the cock is entirely 
eliminated and replaced by a cut-out cock in the cross-over 
pipe between the main trainpipe and the triple valve, the 
same as where the quick-action triple valve is employed. 



The Combined Freight -Car Cylinder, Reservoir 
and Triple Valve* 

The Combined Freight-Car Cylinder and Reservoir 
(Plate 19) is the usual form of equipment applied to a 
freight car. Upon some cars, the cylinder and auxiliary 
reservoir are separated, but the triple valve, auxiliary 
reservoir, and brake cylinder are the same in both cases. 

Auxiliary reservoir 10 is simply a hollow shell for the 
purpose of storing air for use in the brake cylinder upon the 
same car. 

Pipe b provides communication between the triple valve 
and the brake cylinder. Upon passenger cars, this pipe 
does not pass through the auxiliary reservoir, but the 
operation of the brake is the same ; it is simply a different 
arrangement of the same parts. 

2 is the brake cylinder ; 3 is the sleeve in which the 
push rod, connected with the system of brake levers, is 
inserted ; 4 is the non-pressure cylinder head ; 9 is a release 
spring which forces piston 3 to the release position when 
the air pressure is released from the pressure end of the 
cylinder ; 7 is a packing leather which is pressed against the 
cylinder wall to prevent air from escaping past the piston ; 
8 is a round spring packing expander which serves to hold 
the flange of the packing leather against the walls of the 
cylinder ; 6 is the follower plate, which, by means of studs 
and nuts 5, clamps the packing leather to the piston ; and 
a is a small groove (indicated by dotted lines) in the wall 
of the cylinder, called the leakage groove. If the exhaust 
port of the slide valve of the triple valve should, in any 
manner, become obstructed when it is not desired to have 
the brakes applied, a slight flow of air into the cylinder 
from any cause will, instead of forcing the piston out, 

(55) 



ON 

t— ( 

W 
H 
< 




W 
> 

< 
> 

w 

H 
Q 

< 

O 
> 

w 
w 

w 

Q 

l-H 

u 

< 
u 

I 

h 

o 

w 

& 

Q 
w 

I— I 

o 
u 



(56) 



COMBINED FREIGHT-CAR CYLINDER, RESERVOIR AND TRIPLE VALVE. 57 

escape through leakage groove a to the atmosphere at the 
non-pressure end of the cylinder. Valve 17, usually placed 
above the auxiliary reservoir, is known as the release valve. 
A rod extends from the arms of this valve to each side of 
the car, and pulling either rod unseats the valve and dis- 
charges air from the reservoir for the purpose of releasing 
the brake. 



The Pressure-Retaining Valve* 

The Pressure- Retaining Valve (Plate 20) is used almost 
exclusively upon freight cars, except in districts where very 
heavy grades are encountered, where it is also used upon 
passenger cars. 

With the Pressure Retaining Valve in operation, a 
certain portion of the brake-cylinder pressure may be re- 
tained to retard the acceleration of the train while the 
engineer is recharging the auxiliary reservoirs. The 
pressure of the air reserved in the cylinder is determined 
by weight 4, which, in the standard valve, is capable of 
retaining a pressure of fifteen pounds per square inch, which 
has been found by experience to furnish sufficient retarding 
power to prevent a too rapid acceleration of the train speed, 
and to thus provide sufficient time to enable the engineer 
to recharge the train upon heavy grades. 

When handle 5 points downward, the valve is inoper- 
ative for retaining pressure. If the engineer release the 
brakes when the retaining-valve handle is turned down, the 
air from the brake cylinder discharges through the triple 
valve into the retaining-valve pipe (which is screwed into 
the triple-valve exhaust port), through the pipe to the 
retaining valve, which it enters at X, and through ports b, 
a and c to the atmosphere. If handle 5 be turned horizon- 
tally, as shown on Plate 20, the air is discharged from the 
brake cylinder through the triple valve, retaining-valve pipe, 
and ports b, a and b, as before ; but now, port c being 
closed, it must lift weighted valve 4 and pass to the atmos- 
phere through the restricted port d. When the brake- 
cylinder pressure has become reduced to fifteen pounds, 
the weighted valve becomes seated, and the remaining 
fifteen pounds is retained in the brake cylinder until handle 
5 is turned down. 

(58) 



PLATE 20. 




PRESSURE-RETAINING VALVE. 



(59) 



60 PRESSURE-RETAINING VALVE. 

The Pressure- Retaining Valve has nothing whatever to 
do with applying the brake or admitting air into the cylin- 
der ; it simply locks in the brake cylinder fifteen pounds of 
the air pressure that has been supplied through the triple 
valve, and then only if handle 5 has been placed in the 
horizontal position, shown on Plate 20, before the engineer 
increases trainpipe pressure to release the brakes. 

The Improved Pressure- Retaining Valve (Plate 20) 
has a peripheral cavity extending half way round the key, 
through which the air has to pass to reach the weighted 
valve, when the device is in operation. This modification 
is designed to prevent obstruction of the ports, which 
sometimes occurred with the old form of construction, in 
which the cavity was replaced by a slot extending through 
the key. 

Failure of the Pressure- Retaining Valve to hold air in 
the brake cylinder is generally due to a leak in the connect- 
ing pipe, a frequent seat of trouble being at the union : 
it may also be due to a leak in the brake cylinder or in the 
Retaining Valve, but seldom in the latter. 

The structure should stand vertically ; there should be 
no obstruction to the removal of the cap ; it should be so 
located as to be free of access when the train is in motion ; 
it should be cleaned, but not oiled, every time the remainder 
of the air-brake equipment receives that attention ; both it 
and the connecting pipe should be well secured ; a good 
rubber gasket should be used in the union, and a little 
flexibility should be provided in the pipe leading to it from 
the triple valve. 



Piston Travel. 

The following are commonly used terms and their 
definitions. 

Standing Travel — The distance the piston is forced 
outward in applying the brake upon a car when not in 
motion. 

Running Travel — The distance the piston is forced 
out in applying the brake upon a car when in motion. 
The running travel is always greater than the standing 
travel, the increase being due to slack in loose-fitting 
brasses, to the shoes pulling down upon the wheels, to play 
between boxes and pedestals, and to everything of a similar 
nature that increases lost motion in the brake rigging un- 
der the influence of the motion of the car. 

False Travel — An excessive travel momentarily 
occurring while a car is in motion ; it is due to uneven- 
ness of the track, or to some unusual temporary strain. 

The brake- cylinder pressure resulting from a given 
trainpipe reduction is greater with a short than with a 
long piston travel. 

A piston travel of 8 inches results in a brake-cylinder 
pressure of about 50 pounds, in a full service application 
of the brake. Inasmuch as running travel is generally 
about one and one-half inches greater than standing travel, 
the standing travel should be 6^ inches to secure this 
result while running. An automatic slack adjuster is the 
only means of adjusting piston travel so closely ; but, 
where one is not employed, good practice customarily 
requires that the standing piston travel on cars should be 
kept as close as possible to 6 inches. 

A 10-pound reduction of trainpipe pressure results in 
a brake-cylinder pressure more than 50 per cent, greater 
with a 4-inch than with an 8-inch piston travel, 

( 61 ) 



62 PISTON TRAVEL. 

Where the piston travel varies throughout a train, 
a sufficient trainpipe reduction must be made to fully apply 
the brakes having the longest piston travel ; in releasing, 
the increasing trainpipe pressure will force the triple- 
valve piston on the car with an n-inch piston travel to 
release position first, the one on the car with a io-inch travel 
next, and so on down, those with the shortest travel being 
applied with the greatest force and releasing last. 

It will be clear, therefore, that satisfactory operation 
can only be secured by uniformity of piston travel upon all 
cars in a train. If the piston travel be unnecessarily long, 
the brake-cylinder pressure is thereby reduced and the 
efficiency of the brakes correspondingly impaired ; in 
addition, a greater quantity of compressed air is consumed 
in brake applications than would otherwise be necessary, 
thereby entailing greater demands upon the air pump, with 
correspondingly increased wear and tear. If the piston 
travel be too short, it is apt to be accompanied by dragging 
of the brake shoes upon the wheels while the brakes are 
released, and by too high a brake-cylinder pressure, with an 
accompanying liability of sliding wheels, when the brakes are 
applied. The proper piston travel is generally that with 
which there is just sufficient brake-shoe clearance when the 
brakes are released. As already stated, a standing piston 
travel of about six inches has been found to customarily 
meet this requirement. Special conditions undoubtedly oc- 
cur in certain cases under which a uniformly shorter piston 
travel may be very advantageously employed ; in such 
cases, a modification of the brake leverage may perhaps 
also be desirable, on account of the high cylinder pressures 
so resulting. 

In adjusting piston travel, it should be carefully noted 
whether the brake beams are so hung as to be at the same 



PISTON TRAVEL. 63 

height above the rail when the car is light as when loaded, 
or are so hung that they are lowered when the car springs 
are compressed through loading the car and are raised when 
the load is removed. If the brake beams are always at 
the same height above the rail, it is safe to adjust the 
piston travel when the car is either light or loaded ; but if 
the height of the beams varies according to the load in the 
car, it is best, whenever possible, to adjust the piston travel 
when the car is light. If the travel be adjusted when the 
car is loaded, and the brake shoes are consequently in 
their lowest position, wheels are very likely to be slid after 
the car is unloaded, as, the shoes being thereby raised, the 
shoe clearance becomes less and the piston is not required 
to travel so far to bring the shoes up to the wheel tread. 
As a consequence, the piston travel may become too short 
and, the car then being light, flat wheels are likely to result. 
If the piston travel be adjusted when the car is light, the 
shoe clearance becomes increased as the load causes the car 
to settle. This results, of course, in lower brake-cylinder 
pressures and, consequently, in inferior brake efficiency ; 
but the danger of injurious wheel sliding is avoided. 

Piston travel should be adjusted as uniformly as possible 
throughout a train, in which case each brake will more nearly 
do its share of work, there will be fewer flat wheels, and 
smoother braking will result. 



The Automatic Slack Adjuster* 

The Automatic Slack Adjuster is a simple mechanism, 
by means of which a predetermined piston travel is con- 
stantly maintained, compelling the brakes of each car to do 
their full quota of work — no more and no less — thus securing 
from the brakes their highest efficiency, without the flat 
wheels which are likely to accompany a wide range of 
piston travel. 

This device establishes the running piston travel ; that 
is, the piston travel occurring when the brakes are applied 
while the car is in motion ; and, since this is the time during 
which the brakes perform their work, the running travel is 
the important one. Hand adjustment necessarily relies 
upon the standing travel, and it is only coarsely graded, at 
best, by the spacing of the holes in the dead-lever guide. 

The Automatic Slack Adjuster is illustrated on Plates 
21 and 22, and its operation is very simple. The brake- 
cylinder piston acts as a valve to control the admission and 
release of brake-cylinder pressure to and from pipe b (Plate 
21 ) through port a in the cylinder, this port being so located 
that the piston uncovers it when the predetermined piston 
travel is exceeded. Whenever the piston so uncovers port 

a, brake-cylinder air flows through pipe b into slack-adjuster 
cylinder 2, where the small piston 19 (Plate 22) is forced 
outward, compressing spring 21. Attached to piston 
stem 23 is a paw r l, extending into casing 24, which engages 
ratchet wheel 27, mounted within casing 24 upon screw 4 
(Plate 21). When the brake is released and the brake- 
cylinder piston returns to its normal position, the air pres- 
sure in cylinder 2 escapes to the atmosphere through pipe 

b, port a and the non-pressure head of the brake cylinder, 
thus permitting spring 2 1 to force the small piston to its 

(64) 



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(66) 



AUTOMATIC SLACK ADJUSTER. 67 

normal position. In so doing, the pawl turns the ratchet 
wheel upon screw 4, and thereby draws lever 5 slightly in 
the direction of the slack-adjuster cylinder, thus shortening 
the brake-cylinder piston travel and forcing the brake 
shoes nearer the wheels. As the pawl is drawn back to its 
normal position, a lug on the lower side strikes projection a 
(Plate 22) on the cylinder, thus raising the outer end of the 
pawl, disengaging it from the ratchet wheel, and permitting 
the screw to be turned by hand if desired. 

To apply new shoes, turn casing 1 to the left, thus 
moving lever 5 toward the position shown on Plate 21, until 
sufficient slack is introduced in the brake rigging. To 
bring the shoes closer to the wheels and shorten the piston 
travel, turn casing 1 to the right. 

The screw mechanism is so proportioned that the piston 
travel is reduced only about 1/32 of an inch in each oper- 
ation, which removes danger of unduly taking up false 
travel. 

Port a should be drilled as indicated on Plate 23. 

To avoid the necessity of a bracket to support the 
adjuster, a special cylinder head, provided with a suitable 
lug, has been designed for that purpose, and is now furnished 
with truck, tender, and car cylinders, unless other styles be 
specified. 

After the slack adjuster has been applied and the pipe 
tested for leaks, sufficient slack should be introduced in the 
brake gear, by means of the adjuster, and an entire new set 
of shoes applied. The slack should then be taken up, by 
turning casing 1 to the right, until the standing piston 
travel is from six to six and one-half inches, care being 
exercised to distribute the slack equally on both trucks by 
giving about the same angle to the dead levers. When the 
brake gear of a car, having a proper total leverage, is thus 



68 AUTOMATIC SLACK ADJUSTER. 

equalized, the adjuster will maintain a constant piston travel 
until a full set of shoes has worn out, without any necessity 
of changing the position of the dead levers. 

The dead and live levers should each have such an 
inclination, when new shoes are applied to the wheels, that 
they shall have corresponding inclinations in the opposite 
direction when the shoes have become worn out. The 
proper inclination of the dead lever is established by securing 
the upper pin at a distance half the wearing thickness of the 
shoe nearer a vertical plane through the axle than that 
of the brake-beam clevis pin from the same plane, when new 
shoes are applied to the wheels. The proper inclination of 
the live lever is then secured by making the connecting rod 
or strut between the levers shorter, if outside hung-brakes, 
or longer, if inside hung-brakes, than the distance between 
the two brake-beam-clevis pins, by the wearing thickness of a 
shoe, the distance between the two brake-beam pins being 
measured when the shoes are all new and applied to the 
wheels. 

If the piston travel become too short, it will be found 
that either some of the slack in the brake rigging has been 
taken up by the hand brake, where the two work in oppo- 
sition, or the dead levers have been moved. 

If the piston travel is found to be too long, when the 
small pipe leading to the adjuster cylinder is free from ob- 
struction and the packing leather in the adjuster cylinder 
is free from leakage, it is more than probable that the slack 
has been taken up through an application and only partial 
release of the hand brake, and subsequent full release oc- 
curred only after the shoes had had time to wear more or less. 

The best results are obtained by the use of copper pipe 
from the brake cylinder to the adjuster cylinder, since this 



AUTOMATIC SLACK ADJUSTER. 



6 9 



pipe is more flexible and does not corrode. It should 
always be firmly secured. 

Every time the brake cylinder is cleaned and oiled, the 
slack-adjuster cylinder should obviously receive the same 
attention ; and, after each cleaning and oiling, a test of the 
brakes should also include one of the adjuster. 



PLATE 23. 



PORTJO BE,8f FROM, PRESSURE HEAD. 




METHOD OF DRILLING BRAKE CYLINDER FOR SLACK- 
ADJUSTER PIPE CONNECTION. 



PLATE 24. 



J3, U 




AIR-SIGNAL SYSTEM DETAILS. 

(70) 



The Train Air-Signal System* 

Plate 26 shows the general arrangement of the parts 
of the Train Air-Signal System upon a locomotive, tender 
and car ; a more detailed description of the arrangement 
will be unnecessary. This Plate is not intended to show 
the exact location of the parts, but is a diagrammatic illus- 
tration of the general arrangement only. 

Description of Parts. 

The Improved Reducing Valve. 

Fig. 4, Plate 24, shows the Improved Reducing Valve. 
An air pressure of 40 pounds should be carried in the signal 
system, and it is the function of this valve to reduce the main- 
reservoir pressure to this standard for use in the signal pipe. 

7 and 10 are the reducing-valve piston and stem, which 
are supported by the tension of spring 13 and lowered by 
the pressure in chamber C, when sufficient to overcome the 
tension of the spring ; 4 is the supply valve, which is moved 
from its seat by the stem of piston 7 and is seated by the 
tension of spring 6. 

The tension of spring 13 is so adjusted, by regu- 
lating nut 14, that an air pressure of 40 pounds in chamber 
C is required to depress piston 7. When the valve is in 
the position shown, air from the main reservoir enters 
through the pipe connected at A, and, as indicated by the 
arrows, flows through chamber C into the signal pipe con- 
nected at B. As soon as signal-pipe pressure reaches 40 
pounds, the pressure in chamber C forces piston 7 down 
and allows valve 4 to seat. No more air can then enter 
the signal pipe until, through leakage or otherwise, the 
signal-pipe pressure becomes reduced so that spring 13 
may raise piston 7 to unseat supply valve 4. 

(71) 



72 TRAIN AIR- SIGNAL SYSTEM. 

The Old-Style Reducing Valve. 

In the Old-Style Reducing Valve (Plate 25), the ten- 
sion of spring 9, between cap 3 and diaphragm 7, forces 
supply valve 5 from its seat, whenever the air pressure act- 
ing upon diaphragm 7 is insufficient to compress the 
spring. The parts being in the positions shown in the 
cut, air from the main reservoir enters at Z, passes unseated 
valve 5 into chamber A below diaphragm 7, and discharges 
into the signal pipe at Y. When the pressure below dia- 
phragm 7 becomes sufficient to overcome the tension of 
regulating spring 9, diaphragm 7 is thereby raised, and 
valve 5 is seated by the tension of spring 10. A subse- 
quent reduction of signal-pipe pressure permits regulating 
spring 9 to again force diaphragm 7 down and unseat 
valve 5. 

The Signal Valve. 

In the Signal Valve (Fig. 1, Plate 24), the two com- 
partments A and B are separated by diaphragm 12, and 
diaphragm stem 10, secured thereto, extends through 
bushing 9, its end acting as a valve on seat 7 of cap nut 16, 
above passage e. Diaphragm stem 10 fits bushing 9 snugly 
for a short distance below its upper end, to where a per- 
ipheral groove is cut in the stem, below which it is milled 
in triangular form. The air enters the signal valve at Y 
and flows through port d, charging chamber A, and through 
passage c, passing stem 10, into chamber B. The whole 
being charged, a sudden reduction of pressure in the signal 
pipe reduces the pressure in chamber A, above dia- 
phragm 12, and the unreduced pressure in chamber B, act- 
ing upon its lower surface, forces diaphragm 12 upward and 
momentarily permits air to escape from the signal pipe and 
chamber B to the whistle, through a pipe attached at X. 



PLATE 25. 




* re Signal p/pe. 



TO MAW RESERVOIR. 



OLD-STYLE REDUCING VALVE. 



(73) 



^4 TRAIN AIR-SIGNAL SYSTEM. 

The resulting blast of the small signal whistle (Fig. 3), 
located in the locomotive cab, is a signal to the engineer. 
The same sudden reduction of pressure also operates upon 
the reducing valve to cause air from the main reservoir to 
flow into the signal pipe and restore the pressure. Equilib- 
rium of pressure quickly occurs in chambers A and B, and 
the valve at the end of stem 10 returns to its seat. 

The Car Discharge Valve. 

The Car Discharge Valve (Fig. 2) is usually located 
outside of the car, above the door and opposite the opening 
through which the signal cord passes. A branch pipe 
extends from the main signal pipe to the Car Discharge 
Valve, and in this pipe is placed a one-half-inch cock, by 
means of which the valve on the car may be cut out when 
desired. 

Each pull upon the signal cord causes lever 5 to open 
valve 3, permitting a small quantity of air to escape from 
the signal pipe, and thereby causes a signal to be trans- 
mitted to the engineer, through the operation of the Signal 
Valve and Whistle, as previously described. 

General. 

Inasmuch as any discharge of air from the signal pipe 
causes the air whistle to sound on the locomotive, it is obvious 
that all air-signal pipes should be perfectly tight, so that 
signals may not be incorrect and may not occur when not 
intended. 

An interval of three seconds, in which to assure re- 
charging of the signal pipe, should be permitted to elapse 
between successive discharges of air from the car discharge 
valve. Upon trains of exceptional length, this time inter- 
val should be slightly increased. 



£-« 








TRAIN AIR-SIGNAL SYSTEM. 



TRAIN AIR-SIGNAL SYSTEM. 75 

Wherever possible, the Reducing Valve and Signal 
Valve should be so located inside the cab that they will be 
protected from both cold and excessive heat. 

The signal-pipe air strainer upon the car should always 
be located as indicated upon Plate 26. 

A special form of air-strainer is now provided for use 
between the main reservoir and the reducing valve upon 
locomotives. 



The High-Speed Brake* 

The High-Speed Brake, illustrated on Plate 27, is 
a modification of the Quick-Action Air Brake, through the 
addition of the appliances outlined in red. A further mod- 
ification is made in the standard equipment, by substituting 
a quick-action triple valve for the plain triple valve usually 
employed upon the tender, and also by the use of a special 
plain triple valve to operate the driver and truck brakes. 
The names, method of connecting, and the adjustment 
of the parts are indicated on this Plate, and the construction 
and operation of the parts, with the exception of the 
Automatic Reducing Valve, have been explained in other 
parts of this book. 

The locomotive equipment of Plate 27 may be 
changed from the Quick-Action to the High-Speed Brake 
by simply turning two handles — that of the reversing cock 
and that of the quarter-inch cut-out cock in the pipe leading 
to the 90-pound pump governor. When these handles are 
in the positions shown on Plate 27, the 70-pound feed valve 
and the 90-pound pump governor are in service, so that 
the locomotive is ready to operate the ordinary Quick- 
Action Brake ; 70 pounds pressure is carried in the train- 
pipe when the brake valve is in running position, and the 
pump will stop when main-reservoir pressure reaches 90 
pounds. 

If the reversing-cock handle be turned to the opposite 
position and the handle of the quarter-inch cock in the 90- 
pound-governor pipe be turned at right angles to its present 
position, the no-pound feed valve and the high-pressure 
pump governor will become operative and, in the running 
position of the brake valve, no pounds trainpipe pressure 
and a main-reservoir pressure to correspond with the ad- 
justment of the high-pressure governor will result. 

(76) 



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HIGH-SPEED BRAKE. 



HIGH-SPEED BRAKE. 77 

The Duplex Pump Governor consists simply of two 
diaphragm portions of the ordinary pump governor (only 
one of which operates at a time) connected with one steam- 
valve portion. A description of this governor would be but 
a repetition of the description of the pump governor in 
another part of this book. 

The principles involved in the High-Speed Brake 
were discovered some years ago in a series of experiments 
known as the Westinghouse-Galton tests. 

These principles are that (a) the friction between 
the brake shoe and the wheel, which tends to stop the rota- 
tion of the wheel, becomes less as the rapidity of rotation 
of the wheel increases, and that (b) the adhesion between 
the wheel and rail remains practically constant regardless 
of the speed. It will thus be seen that, at high speeds, a 
greater brake-cylinder pressure, with corresponding in- 
crease of the brake-shoe pressure, can be used without 
danger of sliding wheels ; but it is necessary to provide 
means for reducing this high cylinder pressure as the speed 
of the train is decreased. This is accomplished by the 
Automatic Reducing Valve, shown in vertical cross section 
on Plate 28, Fig. 1. A horizontal cross section of this 
valve, through the point at which the connecting pipe to the 
brake cylinder is secured, is shown in Fig. 2. Plate 29 
illustrates the application of the valve to a car, and Figs. 
1, 2 and 3 of Plate 30 are vertical cross sections of the 
upper part of the valve, illustrating the various positions 
of the slide valve, as indicated. 



The Automatic Reducing Valve* 

When air enters the brake cylinder from the auxiliary 
reservoir, it has free access to the Reducing Valve through 
a pipe connected at Z (Plate 28, Fig. 2), so that chamber d, 
above piston 4, is always subject to brake-cylinder pressure. 
Regulating spring 11, adjusted by nut 12, provides a re- 
sistance to the downward movement of piston 4, which is 
finally arrested by spring box 3. Combined with piston 4 is 
its stem 6, fitted with two collars which control the move- 
ments of slide valve 8. Slide valve 8 (Plate 30) is pro- 
vided with a triangular port b in its face, which is always 
in communication with chamber d. Port a in the slide- 
valve seat leads directly to the atmosphere, through exhaust 
opening Y (Fig. 1, Plate 28). 

In Fig. 1, Plate 28, slide valve 8 and its piston 4 are 
shown in their normal positions, occupied so long as brake- 
cylinder pressure does not exceed 60 pounds. 

It will be noted that, in release position (Plate 30, Fig. 
1 ) , port b of slide valve 8 does not register with port a of 
its seat, so that, when the brakes are applied, the air pres- 
sure is retained in the brake cylinder and is subsequently 
released in the usual way, unless it become sufficiently great 
to overcome the tension of spring 11 and force piston 4 
downward. 

When brake-cylinder pressure begins to exceed 60 
pounds in a heavy service application, the pressure upon 
piston 4 moves it downward until port b in the slide valve 
registers with port a in its seat, as shown on Plate 30, Fig. 
2, in which position any surplus brake-cylinder pressure is 
promptly discharged to the atmosphere. Spring 11 then 
raises the piston and slide valve to their normal positions 
(Plate 28, Fig. 1), closing the exhaust port and retaining 
60 pounds pressure in the brake cylinder. In the operation 

(78) 



PLATE 28. 




Fig. 1 



z^to brake cylinder 
Fig. 2. 



AUTOMATIC REDUCING VALVE. 

(79) 



So AUTOMATIC REDUCING VALVE. 

just described, the greatest width of port b is exposed to port 
a, and these ports are so proportioned that, in this particular 
position, the surplus air is discharged from the cylinder 
fully as rapidly as it is admitted through the service-ap- 
plication port of the triple valve. 

The positions assumed by piston 4 and slide valve 8 in 
an emergency application of the brakes, are shown on Plate 
30, Fig. 3. The violent admission of air into the brake cyl- 
inder then so suddenly increases the pressure that piston 4 is 
forced to the lower end of its entire stroke, in which position 
the apex of triangular port b in the slide valve is brought 
into register with port a, and a comparatively slow dis- 
charge of brake-cylinder pressure takes place while the train 
is at its highest speed; but the area of the opening of port b 
gradually increases as the reducing pressure above piston 4 
permits spring 11 to slowly raise the piston and slide 
valve. The rate of the discharge thus increases as the 
speed of the train decreases, until, finally, when the brake- 
cylinder pressure has become reduced to 60 pounds, port 
a is closed, and the remainder of the brake-cylinder pressure 
is retained until released in the usual way through the triple- 
valve. 

When an emergency application of the brakes occurs 
at high speeds, there is little danger of wheel sliding, and 
it will be observed that port b is so shaped that brake- 
cylinder pressure escapes slowly ; while, at low r er speeds, 
where a heavy, service application is more likely to occur, 
and there is a greater tendency toward wheel sliding, the 
base of triangular port b is exposed, allowing brake- 
cylinder pressure to reduce quickly. 

It is essential that Automatic Reducing Valves should 
be occasionally inspected, to prevent possible leaks through 
the discharge port. 



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(81) 



82 AUTOMATIC REDUCING VALVE. 

Cars not equipped with the Automatic Reducing Valve 
should not be attached to trains employing the High-Speed 
Brake, unless the brake cylinders are equipped with the 
safety valve provided for temporary use in such cases. 
The Safety Valve (illustrated on Plate 31) has been es- 
pecially designed to prevent a higher than standard pres- 
sure in the brake cylinders of cars not equipped with the 
Automatic Reducing Valve ; it may be quickly screwed 
into the oiling hole of the brake-cylinder head, and re- 
moved when the cars are again placed in ordinary service. 





Fig. 3. 
5ition of ports. 

ERGENCY STOP. 



PLATE 31. 




a_ 1/- pipe 
tiT'l tap 



SAFETY VALVE. 



<s 3 > 



High-Pressure Control, or Schedule U* 

The High-Pressure Control Equipment is illustrated 
on Plate 32. It consists of simple appliances, by means of 
which the engineer can change the trainpipe and main- 
reservoir pressures from one predetermined standard to 
another, at will. 

This equipment is particularly adapted for use upon 
heavy grades, where " empties" are hauled up the grades 
and " loads " down, a pressure of 70 pounds being carried 
in the trainpipe when the cars are empty, but increased to 
90 pounds when the cars are loaded. If the high pressure 
were carried with empty cars in the train, flat wheels would 
be apt to result ; but, when the cars are loaded, the higher 
braking power is so moderate a proportion of the total 
weight of the car and its contents that danger of wheel 
sliding is practically eliminated. 

The following table illustrates the different relative 
conditions, the figures being based upon a braking power of 
70 percent, of the light weight of an ordinary 60,000-pound 
freight car, when a 70-pound trainpipe pressure is employed. 
In an emergency application of the brakes, the brake-cylin- 
der pressure is, of course, 60 pounds ; while, in a service 
application, the cylinder pressure is 50 pounds. 



KIND OF 


EMPTY OR 


BRAKING POWER IN PER 


APPLICATION. 


LOADED. 


CENT. OF TOTAL WEIGHT. 


Emergency 


Empty 


70 


a 


Loaded 


22.1 tO 23.8 


Service 


Empty 


58.3 


n 


Loaded 


18.4 to 20 



(84 ) 



HIGH-PRESSURE CONTROL, OR SCHEDULE U. 85 

This table shows that the braking power is so small a 
proportion of the weight, when a car is loaded to its full 
capacity, that, even with a trainpipe pressure of 90 pounds, 
there is ordinarily no danger of sliding wheels. 

The differences between the Schedule U and High- 
Speed Brake Equipments are as follows : No additional 
parts are used on the cars with Schedule U ; Safety Valves 
take the place of the Automatic Reducing Valves in the 
locomotive and tender equipment ; Plain Triple Valves are 
used with both locomotive and tender brakes, and the 
piping to the Duplex Pump Governor is changed in one 
particular. 

The description of the High-Speed Brake Equipment 
upon the locomotive applies also to that of the locomotive 
equipment with the High-Pressure Control Apparatus, ex- 
cept the effect produced by the change in the governor 
piping, which is as follows : The reversing-cock handle 
being in the position shown in the diagram, causing the 70- 
pound feed valve and the 90-pound pump governor to be 
operative, the entire brake apparatus will operate in the 
usual manner, except under one condition. Where the 
pump governor is piped to the brake valve in the usual 
manner, it cuts off the steam supply to the pump when 
main-reservoir pressure has attained its ordinary maximum 
limit ; but when it is piped to the chamber in the feed-valve 
bracket, as is the case when Schedule U is used, main- 
reservoir pressure is cut off from action upon the diaphragm 
of the pump governor when the brake-valve handle is in the 
Lap, Service Application or Emergency Application 
Position. It thus occurs that, although the main -reservoir 
pressure is operative upon the 90-pound pump-governor 
diaphragm in the Running Position of the brake-valve, it is 
inoperative when the brakes have been applied and 



86 HIGH-PRESSURE CONTROL, OR SCHEDULE tf. 

the valve handle has been returned to "lap,'* and main- 
reservoir pressure may then be pumped up to the limit 
established by the high-pressure governor diaphragm. 
This high main-reservoir pressure insures a prompt release 
and quick recharging of the brakes upon a long train, and 
the pump has to operate against the high pressure only 
during the time that the brakes are applied. 

Whenever loaded trains are to descend long, heavy 
grades, the handle of the reversing cock is turned to its 
opposite position, thus cutting out the 90-pound governor 
and the low-pressure feed valve. The trainpipe pressure is 
then controlled by the high-pressure feed valve. The 
brakes are then operated in the usual manner ; but, as the 
trainpipe and auxiliary-reservoir pressures are now 90 
pounds, a much more powerful brake application is avail- 
able if desired. 

The purpose of the safety valves connected with the 
driver and tender brake cylinders is to prevent the accu- 
mulation of a higher cylinder pressure than 50 pounds. 

Description of the parts of the High-Pressure Control 
Apparatus, not described under this caption, will be found 
in other parts of this book. 

When carrying a trainpipe pressure of 90 pounds upon 
freight trains, a trainpipe reduction of about 25 pounds 
will be necessary to equalize auxiliary-reservoir and brake- 
cylinder pressures, with the customary average piston 
travel. 



T/?VCA- G/?AX£ ttS£KVO/K 




VALVC 




SI.ACK s40*jvs-r£*9 



£T/V<S/AS£r TRUCK 

0s?a ke: c -tl /svo£K 



PLATE 32. 









TStt/C/r 0/tAK£ K£SCrtVO/n 










HIGH-PRESSURE CONTROL, OR SCHEDULE U. 



Handling Brakes in Train Service. 

Very accurate stops of passenger trains should be 
made with two applications of the brakes. In releasing after 
the first application, place the brake-valve handle in Release 
Position just long enough to release the brakes, and then 
place it on "lap," to avoid overcharging the trainpipe 
and to secure prompt response of the triple valves in the 
second application. 

Always release the brakes of a passenger train just be- 
fore it comes to a standstill, to allow the trucks to 
right themselves: if this rule be observed, disagreeable 
shock to passengers at stopping will be avoided; if on a 
heavy grade, reapply the brakes with sufficient force to pre- 
vent the train from drifting. 

In making stops with a freight train, never release the 
brakes until the train has come to a standstill: partings of 
the train are thus avoided. 

The best way to take water on a locomotive hauling a 
freight train is to stop short of the water plug, cut off, and 
run up with the locomotive alone. 

In setting out cars, always leave the brakes applied on 
the train when leaving it ; then, after recoupling, the train 
cannot be started if the angle cocks have not been opened. 

Before starting, insist upon a test of the brakes and 
upon knowing the number of cars, the number of air 
brakes in good order and the train tonnage, and get all the 
general information concerning the train conditions that can 
be obtained. 

In order to avoid failure of the brakes to release, 
always couple the locomotive to an empty or partially 
charged train with a reduced trainpipe pressure on the 
locomotive. 

If a train pulls hard, do not conclude that the brakes 

(8 7 ) 



88 HANDLING BRAKES IN TRAIN SERVICE. 

are necessarily at fault, and keep trying to "kick" 
them off by repeatedly moving the brake-valve handle into 
the Release Position. If thereby trainpipe pressure be- 
come greater than that for which the feed valve is ad- 
justed, any subsequent trainpipe leakage will cause the 
brakes tc "creep" on, and, in a hard pull, this may 
result in ' ' stalling. ' ' 

Never open the locomotive throttle immediately after 
releasing the brakes upon a freight train ; parting of the 
train may be the result : allow the train slack to adjust 
itself before applying steam. 

The use of the emergency application on turntables is 
objectionable, as it causes severe strains therein; use two 
applications of the brakes instead, or a little steam if stop- 
ping a trifle too soon. This suggestion also applies to 
water-crane stops with a locomotive. 

A heavy, initial application of the brakes has become 
the successful practice in making stops with fast passenger 
trains, and also with loaded freight trains upon heavy 
grades. 

Apply the brakes as soon as the train passes a sum- 
mit, to ascertain what they are capable of doing ; do not 
wait until the train attains maximum schedule speed before 
making an application: the latter practice is sometimes 
the cause of runaways, and gives the brakemen a poor op- 
portunity to stop the train by hand, if necessary. 

The man who appreciates the fact that he has an insuffi- 
cient number of air brakes in good order to control a train 
and calls for the aid of some hand brakes, is a safer man 
for a railroad company than the one who calls for no aid, 
through fear that the trainmen will think ' ' he has lost his 



nerve. ' ' 



When hand brakes are necessary in addition to the 



HANDLING BRAKES IN TRAIN SERVICE. 89 

air brakes in use, first apply those on the cars with the air 
brakes cut out, if practicable, and then those on the cars 
immediately back of the air-braked cars. 

It is wrong to think that the full power of the air 
brake is available upon cars upon which the hand brakes 
have already been applied, in case it is necessary to stop: 
this practice is sometimes a costly one. 

In descending a grade, always aim to keep the train- 
pipe pressure as near the standard as possible; this is ac- 
complished by recharging as frequently as may be neces- 
sary for the purpose : this practice gives greater security, 
if occasion demands that a stop be made. 

Where pressure-retaining valves are used, make a 
practice of using them all, either in passeng eror freight 
service, unless the train will run at too slow a speed with all 
of them in use. 

Always use Release Position of the brake valve to re- 
lease brakes, regardless of the length of the train; this 
practice reduces to a minimum the number of flat and 
broken wheels resulting from failure of brakes to re- 
lease. 

In descending heavy grades with freight trains, always 
recharge in Release Position. If it appears that the train- 
pipe pressure will be too high before it is necessary to again 
use the brakes, return the valve handle to Running Posi- 
tion when the standard pressure has been obtained. In 
case the valve handle is so returned to Running Position 
with a long train, allow it to remain there a few seconds, 
then move it to Release Position for an instant, and return 
it to Running Position : this is to secure the release of any 
brakes that may have applied to the forward cars, through 
the tendency, upon long trains, of the auxiliary reservoirs 
at the forward end of the train to charge a trifle faster than 



£6 HANDLING BRAKES IN TRAIN SERVICE. 

those at the rear. When the brake -valve handle is first 
returned to Running Position, the equalization of pressure 
throughout the trainpipe tends to cause brakes at the for- 
ward end to apply lightly. 

In service applications, a twenty-pound trainpipe re- 
duction, or twenty-five at the utmost, is sufficient to fully 
apply the brakes ; any further reduction is simply a waste 
and loss of trainpipe air. 

In using sand, get it upon the rail before the speed of 
the train has been so reduced that wheels are likely to slide; 
if sand be used while wheels are sliding, bad flat spots are 
produced, since the application of sand will not cause slid- 
ing wheels to revolve. 

Remember that the driver and tender brakes, in good 
condition, will hold considerably more than reversing the 
engine, and that flat tires result if the engine be reversed 
when the driver brakes are already applied. 

Keep driver and tender brakes in good order; for, on 
the heavy classes of freight engines, these two brakes furn- 
ish as much braking power as from five to seven 60,000- 
pound-capacity cars having a light weight of 30,000 pounds. 

Watch the air gauge as closely as possible. 

Trainpipes that are practically tight, those that have 
considerable leakage, and those that leak comparatively 
slightly are found in freight service. Where considerable 
leakage exists, its influence upon brake applications at once 
attracts attention to its existence ; where the leakage is 
comparatively slight, however, it is an element of serious 
danger upon grades, unless the air gauge is frequently ob- 
served. The brakes having been applied by a moderate 
trainpipe reduction, the leakage increases the force of 
application ; and it would be a serious situation if a stop 
from schedule speed were required after the trainpipe and 



Handling brakes in train service. 91 

auxiliary-reservoir pressure has become reduced to 50 
pounds. 

Remember, when stopping a freight train, that poor 
judgment may cause considerable damage to cars and 
lading. 

If the brakes apply suddenly, without apparent cause, 
' ' lap ' ' your brake valve immediately in order to save the 
main-reservoir air and to have sufficient pressure with which 
to release the brakes and recharge the auxiliary reservoirs : 
probably a hose has burst or a conductor's valve has been 
opened. 

In a case of parting between air-braked cars of a 
partially equipped train, close the throttle and do not try 
to pull away, or the head end will only be hit the harder. 
You cannot pull a train with the brakes applied, and the 
cars at the rear, not equipped with air brakes, are bound 
to force the rear into the forward section of the train. 

Trying to release the brakes by placing the brake valve 
in Running Position is the cause of many flat and broken 
wheels. In this position of the brake valve, trainpipe 
pressure rises comparatively slowly; and, if there be any 
poorly fitting triple-valve-piston packing rings, the trainpipe 
air may feed past such pistons and recharge the auxiliary 
reservoirs without forcing the pistons to release position. 
The wheels of such cars may catch and slide upon a poor rail 
when the train is moving slowly ; or the brakes, if applied 
for a considerable time, may heat the wheels sufficiently to 
cause breakage. 

Always make a running test with passenger trains after 
leaving terminals or where engines have been changed. A 
running test is also conducive to the safety of freight trains, 
if a suitable place can be found for such purpose. 

Hand brakes should be used at the rear of a train par 



92 HANDLING BRAKES IN TRAIN SERVICE. 

tially equipped with air brakes, when backing; also to hold 
slack when portions of the train are standing on each side 
of a knoll. 

Applying hand brakes upon rear cars, to avoid shock 
in the caboose when the air brakes are applied upon the head 
end of a train partially equipped with air brakes, often 
produces the opposite effect, since the few hand brakes only 
serve to stretch out the train, so that there is more slack to 
run in and cause increased shock. 

In actual cases of emergency, place the brake-valve 
handle in Emergency Application Position and permit it to 
remain there until the train has come to a standstill, or, if a 
passenger train, until the danger has been removed. 

The shorter the train, the shorter will be the discharge 
at the trainpipe exhaust port, in response to a given reduc- 
tion of pressure in the equalizing reservoir; this know- 
ledge should indicate to the engineer whether the angle 
cocks are open between the tender and cars. 



Piping. 

In piping cars, the following points should always be 
borne in mind : No deviation should ever be made from 
the sizes of pipe specified in our current Catalogue ; 
red lead, if used at all, should be applied sparingly, and 
never inside of fittings ; fins should always be removed from 
pipe before it is installed ; pipe should never be installed 
without first being blown out by steam or air, and the pipe 
should be jarred while being blown out, in order to help 
loosen scale ; long, easy bends should be substituted for ells 
and sharp bends, wherever possible ; all pipe joints should 
be tested under pressure with soapsuds to detect leaks ; if 
there is to be any inclination of the pipe on a car, the high- 
est point should be at the center of the car, and sags in the 
pipe, forming pockets where moisture may collect, must be 
avoided ; all pipe should be securely clamped to the car to 
avoid vibration, which eventually produces leaks ; spe- 
cial care should be given to the M. C. B. recommendations 
concerning the location of the angle cock, in order that the 
hose shall couple properly with foreign cars ; and the angle- 
cock key should clear the nearest part of the car by at least 
one inch. 

Lubricants* 

The following is a list of the lubricants that have 
proved most satisfactory in the different parts of the brake 
system : 

Steam Cylinder of Pump — Valve Oil. 

Air Cylinder of Pump — Valve Oil. 

Brake Valve — High-grade Machine Oil. 

Triple Valve — High-grade Engine Oil. 

Brake Cylinder — a light grease that will not flow in 
summer or become thick in winter. 

(93) 



Brake Inspection and Maintenance* 

Car Inspectors, especially those who do work upon 
air-brake apparatus, should have a thorough understanding 
of its operation, in order to make tests and repairs intel- 
ligently, to recognize defects quickly and to use defect cards 
properly. 

Special care should be exercised to reduce leaks to a 
minimum. Paper should never be used for the purpose of 
stopping leaks in hose couplings, nor should the flanges on 
hose couplings be hammered or bent : this practice some- 
times gives temporary relief, but the standard is destroyed. 
Couplings are often found that will not couple with others ; 
if they be finally forced together and the train breaks in 
two at this point or a switch is made without uncoupling 
the hose, the chances are that either the hose or the train- 
pipe, or both, will be torn off. 

In testing trains with air plants or with a locomotive, the 
following method is commended : After the hose couplings 
are all united and all angle cocks have been opened, 
the air should be turned into the trainpipe. When ample 
time has elapsed to insure a sufficient trainpipe pressure, 
the train should be examined and all leaks stopped. This 
should be given special attention. The brakes should then 
be applied, the piston travel adjusted, where necessary, and 
any defective brakes repaired or carded, according to the 
rules of the road. 

If the grades be sufficiently heavy to warrant a retain- 
ing-valve test, the handles of these valves should be turned 
up before the brakes are released. The retaining-valve 
handles should not be turned down until about a minute 
after trainpipe pressure has been raised sufficiently to cause 
the triple-valve piston to move to release position. If a 
discharge of air does not accompany the turning down of 

(94) 



BRAKE INSPECTION AND MAINTENANCE. 95 

the retaining-valve handle, the retaining valve should be 
repaired or the defect carded. The apparent fault of the 
retaining valve in not holding the air properly may, how- 
ever, be due to a loose pipe joint between the triple valve 
and the retaining valve or to a leaky cylinder packing 
leather. 

In adjusting piston travel, inspectors should be gov- 
erned largely by what is said concerning that subject on 
other pages of this book. 

After the inspection has been completed, in any case 
where the locomotive about to take the train has been used 
in making the test, the engineer and conductor should be 
informed regarding the number of cars in the train, the 
number of air brakes working properly and the number of 
retaining valves in working condition, and should also be 
given any additional information of a general character that 
will aid the engineer in the successful manipulation of the 
brakes. 

Cleaning and Oiling the Triple Valve and 
Brake Cylinder. 

The following points, if borne in mind, will be of 
service in cleaning and oiling triple valves and brake cylin- 
ders: 

Tools that will facilitate the work are the following : 
A monkey wrench ; a hammer and chisel ; a Stillson 
wrench ; a cotter-pin drift ; a lever-pin drift ; a combina- 
tion open-end S wrench that will fit triple-valve nuts and 
cap screws, cylinder nuts, and the nut on the clamp made 
to go over the piston sleeve to keep the release spring in 
compression when the piston is removed ; a double-end 
wrench, one end of which will take the drain-cup union, 
the other to be used in renewing hose ; a can of kerosene ; 
a small sharp-pointed piece of hard wood ; an oil or grease 



96 BRAKE INSPECTION AND MAINTENANCE. 

can ; a squirt can ; hose and union gaskets ; a pair of 
plyers ; waste ; an old piece of chamois or of some cloth ; 
and a suitable box in which to carry the tools. 

The order of work found to be the most satisfactory is to 
first take the triple valve apart and immerse the removable 
internal metal parts in kerosene, leaving them there until 
the work upon the cylinder is completed ; next remove the 
push rod and, if a freight cylinder, put a clamp upon the 
piston sleeve ; remove the cylinder head and piston ; clean 
and oil the cylinder ; and then replace the parts in the 
reverse order. The parts of the triple valve should then 
be thoroughly cleaned and replaced, after which the strainer 
should be cleaned, the brake tested, the piston travel ad- 
justed, the retaining valve tested (and repaired if necessary), 
and, finally, the cylinder should be stencilled to show the 
date of cleaning and oiling. The pipe joints should be 
tested under pressure with soapsuds. The nuts upon the 
bolts which support the cylinder should always be examined, 
and tightened, if loose ; if they are loose, the movement of 
the cylinder, when the brakes are applied, produces leaks 
in the pipe joints. 

In cleaning the cylinder and piston, special attention 
should be given to removing lint, freeing the leakage groove 
of any deposit, and thorough cleansing of the expander 
ring, packing leather, and piston. In oiling or greasing 
the cylinder, special attention should be given to the 
thorough lubrication of the top of the cylinder and the 
inside of the packing leather where the expander ring rests. 
A light grease in the cylinders has been found to give the best 
results. If too much oil be used, it will work back into the 
triple valve and ruin the rubber-seated valve and the gasket. 
It should be particularly observed that the follower nuts 
are tight, since they are frequently found to be loose. 



BRAKE INSPECTION AND MAINTENANCE. 97 

In cleaning the triple valve, special care should be 
given to the slide valve, the graduating valve, the slide-valve 
seat, the packing ring of the triple-valve piston, and the 
emergency rubber-seated valve. In order to avoid springing 
the triple-valve-piston packing ring, it should never be 
removed except for the purpose of renewal. Cloth should 
be used on the triple-valve parts, and a final application of 
the chamois will remove the possibility of trouble from lint. 
The triple-valve-piston packing ring should be caused to 
work freely in its groove before replacing. 

Seven or eight drops of oil are sufficient for lubricating 
the entire triple valve, as none should be used on the quick- 
action parts. The slide valve, its seat, the triple-valve- 
piston packing ring, and the bushing in which it w T orks 
should receive special consideration in respect to sufficient 
lubrication, and care should be taken not to permit any oil 
to get upon the gaskets or rubber-seated valve. 

The graduating and check-valve springs should be 
examined and renewed if they have a material permanent 
set. 

In making yard or shop tests, it is advisable, wherever 
possible, to have an engineer's brake valve with which to 
apply and release the brakes; and the triple valves should be 
subjected to a test that will detect any badly worn triple- 
valve-piston packing rings. 



Foundation Brake Gear* 

To insure a sufficiently strong, durable and substantial 
brake gear, the sizes of rods, levers, and pins recommended 
by the Master Car Builders' Association should be strictly 
followed. 

It is important that the rods should be parallel with a 
longitudinal line through the center of the car when the 
brakes are applied. 

Brake beams should be so hung that the centers of the 
brake shoes shall be at the standard distance above the rail, 
as prescribed by the Master Car Builders' Association ; and, 
wherever possible, the brake beams should be so hung 
that, whether the car be light or loaded, they shall always 
be at the same distance above the rail. This practice greatly 
reduces the liability of flat wheels, since the piston travel is 
not affected by the loading or unloading of the car and 
may therefore be properly adjusted whether the car be 
light or loaded. 

It is always best to so design the hand and air brakes 
that they shall ' ' work together ;' ' that is, so that all the levers 
move in the same direction when the brakes are applied by 
hand as when applied by air. Where they ' ' work op- 
posite, ' ' or where hand power pulls against air power, only 
one can be successfully used at a time, which is very incon- 
venient where the air brake is applied upon cars that are to 
stand for some time on a grade, since the hand brakes can- 
not be applied until the air brakes have been released. 
Many other objections to such an arrangement occur in 
road practice, and brakes that * ' work together ' ' are much 
to be preferred, from the standpoints of both practicability 
and safety. 

In securing brake cylinders to car bodies, an iron plate is 
much to be preferred to wooden blocks, since the latter 

(98) 



FOUNDATION BRAKE GEAR. 99 

shrink, thus loosening the bolts and permitting move- 
ment of the cylinder every time the brakes are applied. 
This movement of the cylinder is imparted to the train- 
pipe and is a very productive source of leaks. 

Triple valves should be so located as to be easy of 
access for cleaning or repairing. 

Levers should stand approximately at right angles to 
the rods when the brakes are applied. 

Fig. 1, Plate 33, illustrates the Hodge system of 
leverage ; Fig. 2 is the Stevens ; and Fig. 3 is the recom- 
mended design for tenders. The usual form of brake 
gear applied to freight cars is illustrated on Plate 35 under 
the subject of ' ' Leverage. ' ' 

The following percentages of their light weights are the 
usual braking powers for the different vehicles of trains : 

Passenger Cars, 90 per cent. ; 

Freight Cars, 70 per cent. ; 

Tenders, 100 per cent. ; 

Driver Brakes, 75 percent, (of weight upon drivers, as 
the locomotive stands ready for service); 

Truck Brakes, 75 percent, (of weight upon the truck). 

Slight modifications of this general practice are some- 
times desirable, to meet special conditions. 



LofC. 



PLATE 33. 




car brake: levers. 



Fig. i 




STEVENS SYSTEM 
C/KR BRAKE LEVERS. 



Fig. 2. 




Fig. 3. 



(100) 



Leverage* 

In every calculation required to determine the proper 
proportions of brake levers, or to determine the forces 
operating upon different pins, two forces and two distances 
are involved : one force is that which may be regarded as 
applied at one of the three pins, and the other force is re- 
garded as that delivered at another of the pins, while the 
remaining pin becomes the ' ' fulcrum ' ' ; the two distances 
involved are those between the fulcrum pin and the pins at 
which the two forces are applied and delivered, respect- 
ively. In every case, the product of the force applied at 
one pin and its distance from the fulcrum pin is equal to 
the product of the force delivered at the other pin and its 
distance from the fulcrum pin. If the applied force be 
designated by T^and its distance from the fulcrum pin by 
a, and if the delivered force be designated by H^and its 
distance from the fulcrum pin by b, then F X a = IVX b. 
When the applied force T^and the distances a and b are all 

known, the delivered force W = — , . If the force W, 

o 

which must be delivered, and the two distances a and b are 

known, the force that must be applied is F = . 

^ r a 

Similarly, if both the applied force /^and the force If 7 that 

must be delivered are known, together with the distance 

of one of the forces from the fulcrum pin, the other distance 

IVXb ...•■• ,. , FXa 

isa = — — , where a is the known distance, or b = — ty^> 

r W 

where a is the known distance. 

It is to be understood, of course, that if a force is 

operative at any one of the three pins, forces must also be 

operative at both of the other two pins ; but the force 

acting at the fulcrum pin does not require consideration in 

(101) 



I02 LEVERAGE. 

determining the relation between the forces acting at the 
other two pins. The force at any one of the three pins 
may, in such calculations, be regarded as the applied force, 
and that at either of the other two may be treated as the 
delivered force, the remaining pin becoming the fulcrum in 
that case. 

There thus appear to be three different sets of condi- 
tions, depending upon the relative position of the fulcrum 
pin ; but the same rules and formulae apply to each. The 
three cases are illustrated, as applied to the truck brake lever, 
on Plate 34. In each of the three cases, the formulae for 
determining the applied and delivered forces and their 
distances from the fulcrum pin are given, and it will be 
observed that the formulae are precisely the same in all three 
cases, except as affected by the following considerations. 

It sometimes occurs that, when the middle pin is 
the fulcrum pin, the applied and delivered forces at the 
end pins are given, but the only distance known is that 
between the end pins. In that case, neither distance a nor b y 
but only their sum, is known. In such a case, it is neces- 
sary to proceed as follows : Let the length of the lever — 
or the distance between the end pins — be represented by /. 
Then, since the middle pin is the fulcrum, /=#+ b, so 
that a = l — b and b = l — a. Substituting these values of 

- ■ . - . IVX b A . FXa 

a and b in the equations a = — ^ — and b= — uz~* re ~ 

.1 • • , j, WX I Jz FX / 

spectively, it is found that a = ^ , TT _ and = = , Tr . . 

F+W F+W 

The values of a and b having been obtained by these 

formulae, the correctness of the computations may always be 

checked, since the sum of the computed values of a and b 

must equal /. 



PLATE 34. 




or a =H— *J_ 
F+W 

or h= F * l 
W F+W 



FULCRUM BETWEEN APPLIED AND DELIVERED FORCES. 




W 



Fxa 



a 

g-ELfe or g = W*d 
F W-F 

b = Z*JL or b= Fxd 
W W-F 

DELIVERED FORCE BETWEEN FULCRUM AND 
APPLIED FORCE. 




Vff =. Fxg 

b 
F a~ 



F*d 



h -^ or &- 



APPLIED FORCE BETWEEN FULCRUM AND 
DELIVERED FORCE* 



(103) 



104 LEVERAGE. 

It sometimes also may occur that both the applied 
force /^at one pin and the force IV that must be delivered 
at another pin are known, but the only additional informa- 
tion is the difference between the distances a and 6, the 
fulcrum being an end pin. Let d represent the difference 
between the distances a and b. Two cases arise. In one 
case, a is greater than b by d inches. Then a = b + d and 
b = a — d. Substituting these values of a and b in the 

IV X b , , F*a 
equations a = — ^ — and o = , respectively, it will 

W* d Fx d ^ 1 t 

be found that a = ~ttj ^ and b = — . I he check 

IV— F IV — F 

is that the calculated value of a must be equal to 

the sum of d and the calculated value of b. 

In the other case, a is less than b by d inches. Then 

a = b — d and b = a -f d; and, in a similar manner, it is 

WX d Jz F X d _ . - . , 

iound that a = — Ttt and <7 = -= — ==; 1 he check is that 

F— IV r — W 

the calculated value of a must be equal to the calculated 

value of b less d inches. 

The force acting at the middle pin of a straight lever 
is always equal to the sum of the forces acting at the other 
two pins, and this fact furnishes the means of checking the 
correctness of calculated forces. 

It is of the utmost importance that the same units of 
force and distance be preserved throughout calculations, 
all forces being preferably expressed in pounds and all 
distances in inches. It is equally important to remember 
that each reference to the distance between pins invariably 
means the distance from center to center of pins or of pin 
holes. 

The following practical example will illustrate the 
method of employing the formulae above given. It is re- 



LEVERAGE. 



I05 



quired to apply the air brake to a freight car weighing 
34,286 pounds. The general construction of the brake 
gear is to be as shown on Plate 35. The live truck lever is 
30 inches long, is secured to the brake beam at the lower end 
and inclines at such an angle (40 degrees from the vertical) 
that the upper end is 19 inches from the center line of the 
car. The middle hole in the lever, for securing the strut 
connection to the dead lever, is 6 inches from the lower 
hole, and is consequently 24 inches from the upper hole. 

As the car weighs 34,286 pounds and the proper 
emergency braking power is 70 per cent, of the light 
weight, the pressure from the four brake beams upon the 
wheels must be 24,000 pounds, or 6,000 pounds per beam. 
The delivered force ( TV) at the lower end of the live lever 
must therefore be 6,000 pounds ; the middle pin is the 
fulcrum ; the distance (£) from the fulcrum to the delivered 
force is 6 inches, and the distance (a) from the fulcrum to 
the applied force (F) at the upper pin is 24 inches. Sub- 
stituting these values of W y a and b in the formula 

WX b 
F = , the force that must be applied at the upper 

• U +U A ' 77 6 >°°° X 6 

pin by the upper rod is r r= = 1,500 pounds. 

To find the force delivered by the live lever, through 
the strut connection, to the dead lever, the lower pin be- 
comes the fulcrum, 1,500 pounds is the applied force (F) 
at the upper pin, 30 inches (a) from the fulcrum, and the 
delivered force ( IV) is 6 inches (b) from the fulcrum. 

TU , TJ/ FX a 1,500x3° 1 ^, 

I herefore, W = — = = 7 , 500 pounds. The 

correctness of this result is checked by adding the forces 
(1,500 pounds and 6,000 pounds) acting at the upper and 
lower pins, respectively, which must equal the force at 
the middle pin. 



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LEVERAGE. 107 

The force applied to the middle pin of the dead lever 

is thus found to be 7,500 pounds. In order that it may 

clear the upper rod, the dead lever is made but 25 inches 

long. The upper pin is the fulcrum and a force of 

6,000 pounds must be delivered to the brake beam at 

the lower pin, 25 inches from the fulcrum, by means of 

the force of 7,500 pounds applied at the middle pin; 

that is, F = 7,500, W = 6,000, and b = 25. 

T , r WX b 6,000 X 25 . _ 

1 hereiore, a = —= — = - = 20 inches. I he 

F 7,500 

middle pin must thus be 20 inches from the upper pin and 5 
inches above the lower pin in the dead lever. It should be 
observed that the lower end of the dead lever is, in the 
case under consideration, one-fourth the length of the 
upper end, just as is the case with the live lever ; and it is 
a very important fact to remember that, in order to obtain 
the same brake-shoe pressure upon each pair of wheels of 
the truck, the dead lever must always be proportioned pre- 
cisely the same as the live lever, though its length may be 
different. Conversely, if the live and dead levers are pro- 
portioned alike, the brake-shoe pressure is the same upon 
both pairs of wheels. 

As the trucks are alike, the above calculations apply 
to each, and it is now only necessary to remember that 
1,500 pounds must be applied at the upper pin of the live 
lever of each truck, at a distance of 19 inches from the 
center line of the car. The upper rods should be parallel 
with the center line of the car when the cylinder and float- 
ing levers are at right angles to them, so that a force of 
1,500 pounds must be delivered at the pins connecting the 
upper rods with the cylinder and floating levers, at a dis- 
tance of 19 inches from the center line of the car. (In the 
release position, as indicated on Plate 35, these distances 



Io8 LEVERAGE. 

from the center line would be somewhat less, so that the 
diagram is not strictly correct in this respect. ) 

The positions of truss rods, etc. , make it most con- 
venient to so locate the brake cylinder that the center line, 
or axis, of the cylinder is 14 inches from the center line of 
the car. The length of the cylinder lever thus becomes de- 
termined by the sum of 19 and 14 inches, and is 33 inches. 
The cylinder being 8 inches in diameter, the emergency air 
pressure upon the piston is 3,000 pounds, which is the 
force (F) applied at the pin at one end of the cylinder 
lever, while the delivered force ( W) at the pin at the other 
end must be 1,500 pounds, the middle pin being the ful- 
crum, and the length (/) of the lever is 33 inches. Neither 
a nor b is known ; but, from the formula for such a case, 

W X / 1,500X33 , . % _. , f t 

a = ^ , Trr = — j — ^- =11 inches. Similarly, 

F+W 3,000+1,500 

f X/ 3,000X33 . , r«* 1 1 

b= _ , rTj r = — : ~— =22 inches. The check 

F+W 3,000+1,500 

upon these calculations is that the sum of a and b ( 1 1 and 
22) equals /, or 33 inches. 

To find the force delivered by the cylinder lever to the 
connecting rod, and thereby to the floating lever, the upper- 
rod pin becomes the fulcrum, a = 33 inches, ^=22 inches 

and F = 3,000 pounds. Therefore, W = — ^ = 

— — 

4,500 pounds, which checks, as the sum of 3,000 and 1,500. 
The connecting rod between the cylinder and floating 
levers should be parallel with the center line of the car. 
As it is 11 inches from the axis of the cylinder, which is 14 
inches from the center line of the car, the connecting rod, 
and therefore the middle pin of the floating lever, should 
be 3 inches from the center line of the car. As already 
found, the upper rod and its pin in the floating lever should 



LEVERAGE. IO9 

be 19 inches from the center line of the car, so that the 
distance between that pin and the middle pin of the floating 
lever must be 16 inches. It remains to determine the posi- 
tion of the fulcrum pin at the other end of the floating 
lever. The force (F) applied at the middle pin is 4,500 
pounds, and the force ( W) that must be delivered at the 
upper-rod pin is 1,500 pounds. We do not know either 
distance a or b; but we know that a is 16 inches less 
than b. Making d = 16 in the formulae for this case, 

JVXd 1,500X16 . - - _ Fxd 

a= ~ — nr=~ — =8 inches, and b = -= — 7 = 

F—W 4,500—1,500 F— W^ 

4,500 X 16 



= 24 inches. These results check properly, 
4,500-1,500 

as 24 — 16 = 8. The fulcrum pin must therefore be located 

8—3 = 5 inches from the center line of the car body. 

It will be observed here, also, that the short end of 
the floating lever is one-half the length of the long end, the 
same as with the cylinder lever; and it is invariably neces- 
sary, in order that the same force shall be delivered to both 
upper rods, that the cylinder and floating levers shall be 
proportioned exactly alike, though their lengths may be 
quite different. Conversely, also, if the cylinder and float- 
ing levers are proportioned alike, the same force is exerted 
upon both upper rods. 

This completes the calculations for the entire brake 
gear, from the brake cylinder to each brake beam, and the 
example has included every kind of brake-lever computa- 
tion that can arise in determining the proportions of 
straight brake levers. 

If the same car were already equipped with the air 
brake and it be desired to ascertain the braking power, we 
should pursue the reverse course. Starting with the known 
emergency piston pressure of 3,000 pounds as the applied 



I IO LEVERAGE. 

force (F) at the end pin of the cylinder lever, the 

middle pin is the fulcrum, a = n and b = 22. Therefore, 

TJ _ fX a 3,000 x 11 j 1 1- 1 , 

W = — - — = = 1,500 pounds, delivered to the 

upper rod. 

Since the floating lever is found to have the same 
proportions as the cylinder lever, we know, without further 
calculation, that a force of 1,500 pounds is also delivered 
by the floating lever to the other upper rod. If the 
floating lever were found to be of materially different 
proportions from those of the cylinder lever, we should 
first find the force delivered at the middle pin of the cyl- 
inder lever, by considering the upper-rod pin as the 
fulcrum, checking the result by adding the forces at the 
end pins. Then, with this force as the applied force at 
the middle pin of the floating lever, we should find the 
force delivered to its upper rod by the floating lever. It 
would then be necessary to continue the calculations through 
to the brake beams of the truck at that end of the car, As it 
is, knowing that 1,500 pounds is the force (F) applied to 
the upper pin of each live truck lever, we have only to 
trace the forces through one truck. 

The applied force (F) at the upper pin of the live 
truck lever is 1 , 500 pounds and the middle pin is the fulcrum, 
so that, in determining the force ( W) delivered to the 

F v ci 

brake beam, a = 24 and b = 6. Therefore, W = —— — 

— = 6,000 pounds, which is the force applied to 



6 
the brake beam. 

As the dead lever is proportioned exactly like the live 
lever, we know, without further calculation, that the same 
force — 6,000 pounds — is applied to each brake beam, and 



LEVERAGE. Ill 

the total braking power of the car is 6,000 X 4, or 24,000 
pounds, which, divided by the weight of the car (34,286 
pounds), is .70 — the per cent, braking power. 

If the dead lever were proportioned materially differ- 
ently from the live lever, it would be necessary to regard 
the lower pin of the live lever as the fulcrum and to first find 
the force delivered at the middle pin, checking the result 
by adding the forces at the upper and lower pins, which 
sum it must equal. With this force applied at the middle 
pin of the dead lever, and with the upper pin as the ful- 
crum, we should then find the force delivered to the brake 
beam at the lower pin. The sum of the forces found to be 
applied to the four different brake beams would then be 
the braking power upon the car. 

The forces above calculated, and shown upon the dia- 
gram of Plate 35, represent an emergency application and 
are designated by the letter E. In a full service appli- 
cation, the air pressure upon the piston of the 8-inch brake 
cylinder is but 2,500 pounds, and the forces thereby de- 
veloped throughout the brake gear are designated upon 
the same diagram by the letter S. The calculation of 
these forces is left as an exercise for the interested reader. 
It may be observed, also, that, where the plain triple valve 
is employed, the forces designated by the letter S occur 
in emergency as well as in full service applications. 

The foregoing example illustrates the method of cal- 
culating the braking power developed by any system of 
straight levers employed in locomotive driver, locomotive 
truck, tender or car brakes, excepting only the cam driver 
brake. If the brake gear includes other levers in addition to 
those of the example illustrated on Plate 35, the same 
methods and formulae are applicable in the extended cal- 
culations. 



112 



LEVERAGE. 



A short method of calculating the braking power de- 
veloped by an American Equalized Driver Brake, of the 
construction shown on Plate 36, is to multiply the total 
force exerted upon the piston (as indicated, for an air pres- 
sure of 50 pounds, in the table below) by the length of the 
long lever arm, divide this product by the length of the 
short arm, and multiply the result by two. 

In calculating the braking power upon locomotive drivers, 
locomotive trucks, tenders, passenger cars and freight cars, 
the force exerted upon the piston depends upon the size of 
the cylinder and the air pressure in the cylinder. Where 
the plain triple valve is used, the air pressure is regarded as 
50 pounds per square inch, while, with a quick-action triple 
valve, 60 pounds per square inch is regarded as the cylinder 
pressure. The following table gives the forces exerted upon 
the pistons of the different sized cylinders with pressures 
of 50 and 60 pounds per square inch : 

Size of Cylinder, 16" 14" 12" 10" 8" 6" 

50 pounds pressure, 10050 7700 5650 4000 2500 1400 
60 pounds pressure, 12050 9200 6700 4700 3000 1700 



Auxiliary Reservoirs Used With Different Sizes 
of Brake Cylinders. 



10" x 24" Auxiliary Reservoirs with 8" Tender and Truck Cylinders; 
" " " 8" Driver Brake Cylinders ; 

" " " 10" Brake Cylinders of all kinds ; 

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leverage. 1 1 3 

Cylinders Used by the American Brake Company 
For Different Weights upon Drivers. 

8" Cylinders — Weight on Drivers up to 40000 lbs. ; 
10" " " " M from 40000 to 85000 lbs,; 

12" " " " " " 70000 " 115000 " 

14" " " " " " 110000 " 170000 " 

iV (< " " <{ <( 145000 " 225000 (< 



The following table shows the proper sizes of Cylinders to be 
used with Passenger Cars and Tenders of different weights : 



Cylinder for Passenger Car. 


Weight of Car. 


10", 
12", 

14", 


Up to 50000 pounds ; 
50000 to 70000 pounds ; 
Above 70000 pounds. 


Cylinder for Tenders. 


Weight of Tender. 


8", 

10", 


Up to 35000 pounds ; 
Above 35000 pounds. 



The American Driver Brake* 

Plate 36 illustrates the American Outside Equalized 
Driver Brake, which has generally superseded the Cam 
Brake, being simpler in design and in adjustment. 

In designing driver brakes, a special effort should be 
made to avoid the use of brake cylinders requiring a stuff- 
ing box, since this is a source of constant trouble, because of 
the fact that the end of the piston rod is required to travel 
in the arc of a circle, traced by the end of the long lever 
arm. As a result, the rod is deflected, wears irregularly 
and becomes very difficult to pack tightly. 

The importance of maintaining a good driver brake 
cannot be emphasized too strongly, in view of the fact that 
the driver-brake power developed upon a consolidation 
engine, weighing 150,000 pounds on the drivers, is 112,500 
pounds. A 60,000-pound-capacity, wooden car usually 
weighs about 30,000 pounds and has a braking power of 70 
per cent. , or 21 ,000 pounds. It thus appears that the driver 
brake alone furnishes more braking power than five such 
60,000-pound-capacity cars. 

An air pressure of 50 pounds is required in the 
driver-brake cylinders to secure the full proper braking 
power. A gauge should be applied to the cylinders, 
and the piston travel should be so adjusted that auxiliary-res- 
ervoir and brake-cylinder pressures equalize at 50 pounds 
when the brake is fully applied. The piston sleeve or rod 
on each side of the locomotive should then be distinctly 
marked next to the cylinder head, while the brakes are 
applied ; this mark is a reliable guide for future adjustment 
of the driver brakes. 

A test of the cylinders for pressure, leakage, etc., 
should be made with an air gauge at regular intervals by 
the person authorized to do this work. 

(1*4) 



PLATE 36. 




o) 



AMERICAN EQUALIZED DRIVER BRAKE. 

(»5) 



Il6 AMERICAN DRIVER BRAKE. 

A light grease has been found the most satisfactory 
lubricant for driver brake cylinders, especially those located 
near the fire box. 

A well-maintained driver brake with flange shoes will 
keep the tires in good condition much longer than where the 
brake receives scant attention. A higher mileage is thereby 
secured, the cost of repairs is less, and a good driver brake 
is always a most important essential to a quick stop. 



The Cam Driver Brake. 

The chief features of the Cam Brake requiring con- 
sideration are the maintenance of such a piston travel 
that auxiliary-reservoir and brake-cylinder pressures shall 
equalize at 50 pounds when the brakes are fully applied, 
and of such an adjustment of the cams that their point of 
contact shall be in line with the piston rod ; otherwise a 
bending influence will be exerted upon the piston rod. 

To adjust the cams, in order to shorten or lengthen 
the piston travel or to secure a central point of contact, the 
check nut should be slacked off and the screw turned out- 
ward to shorten the piston travel, or inward to lengthen it. 

To calculate the braking power, apply the brake and 
measure the piston travel; then release the brake, insert 
pieces of ^-inch steel wire crosswise between the tire and 
shoe at the upper and lower ends, and again apply the 
brake; divide the difference of the piston travels by the 
thickness of the steel, and multiply the result by the total 
force acting upon the piston. The result is the pressure of 
one shoe, which, multiplied by 4, gives the total braking 
power. Divide this total by the total weight upon drivers 
to obtain the percentage braking power. 

EXAMPLE. 

Weight on drivers, 53,330 pounds; 

Piston travel, without inserting wires, 3 inches; 

Piston travel, with ^-inch wires inserted, 2 inches; 

Total force on piston (8-inch-cylinder brake, fully ap- 
plied), 2,500 pounds. 

1-3-^=4. 4 x 2,500 = 10,000 pounds. 

10,000 pounds x 4 = 40,000 pounds — the total brak- 
ing power. 

40,000-4-53,330 = 75%. 

fn 7 ) 



The Locomotive-Truck Brake* 

Plate 37 illustrates the American Equalized Loco- 
motive-Truck Brake with Automatic Slack Adjuster. In- 
asmuch as a considerable proportion of the weight of 
certain types of locomotives is carried upon the truck, the 
importance of a well-designed brake upon that part of the 
equipment is self-evident, especially as the weight upon this 
truck frequently equals (and often exceeds) the weight of 
a large-capacity car. This brake should be maintained in 
a high state of efficiency, which is readily accomplished by 
the aid of the automatic slack adjuster. 

What has been said above, with reference to the main- 
tenance and care of the driver brake, applies with equal 
force to the truck brake. 



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